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Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 16, Iss. 4 — Feb. 18, 2008
  • pp: 2752–2763

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Proposal for ultra-high performance infrared Quantum Dot

A. Rostami, H. Rasooli Saghai, N. Sadoogi, and H. Baghban Asghari Nejad  »View Author Affiliations


Optics Express, Vol. 16, Issue 4, pp. 2752-2763 (2008)
http://dx.doi.org/10.1364/OE.16.002752


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Abstract

In this paper, effect of an introduced defect on electrical and optical properties of quantum box and spherical quantum dot is studied. 3Dself-consistent solution of the Schrödinger-Poisson equations for evaluation of the proposed complex quantum box and analytical solution for spherical quantum dot are used. It is shown that with increasing the defect size and height a considerable enhancement in matrix element, optical nonlinearities (second order, quadratic electro-optic effect and the resonant third order nonlinear susceptibilities), optical linear absorption coefficient (4.5–10 nm, 10−4~10−2 m.V−1, 10−12~10−9 m2/V2, 10−11~10−9 m2/V2 and 4.7×102~3.8×104 cm−1 respectively) and electroabsorption properties associated with intersublevel transition of centered defect quantum dot are examined. Also, it is shown that enhancement of optical nonlinearity is approximately independent of defect position that is so excellent from practical implementation point of view. A THZ-IR photodetector based on resonant tunneling spherical centered defect quantum dot (RT-SCDQD) operating at room temperature is also investigated. Inserting the centered defect in quantum dot increases the dipole transition matrix element and so increases the absorption coefficient considerably (1.05×106~7.33×106 m−1 at 83 µm). Therefore the quantum efficiency in SCDQD structure enhances which leads to increasing the responsivity of the proposed system. The double barrier reduces the dark current. These improvements concludes to ultra high detectivity 5×1016 and 2.25×109 cmHz1/2/W at 83 and 300°K at 83 µm respectively.

© 2008 Optical Society of America

1. Introduction

Low dimensional semiconductor heterostructures such as quantum wells and dots are expected to exhibit enhanced optical properties due to modification in density of states [1

S. Ghosh, A. S. Lenihan, M. V. G. Dutt, O. Qasaimeh, D. G. Steel, and P. Bhattacharya, “Nonlinear Optical and Electro-optic Properties of InAs/GaAs Self-organized Quantum Dots,” J. Vac. Sci. Technol. B. 19, 1455–1458 (2001). [CrossRef]

, 2

E. Rosencher, P. Bois, J. Nagle, and S. Delaitre, “Second Harmonic Generation by Intersubband Transitions in Compositionally Asymmetrical MQWs,” Electron. Lett. 25, 1063–1065 (1989). [CrossRef]

]. The large dipole transition and oscillator strengths in infrared range associated with intersubband transition (ISBT) in quantum confined semiconductor nanostructures have given rise to substantial interest and research in both fundamental physics study and development of infrared optoelectronic devices [3

S. Banerjee and K. A. Shore, “MIR and NIR Nonlinear Optical Processing using Intersubband χ (3) in triple Quantum Well Structures,” Inst. Phys. Publish. UK. 655–660l (2003).

,4

T. Brunhes, P. Boucaud, S. Sauvage, F. Glotin, R. Prazeres, J. -M. Ortega, A. Lemaitre, and J.-M. Gerard, “Midinfrared Second-harmonic Generation in P-type InAs/GaAs Self-assembled Quantum Dots,” Appl. Phys. Lett. 75, 835–837 (1999). [CrossRef]

]. Compared with two-dimensional quantum well structures, the intersubband transition in quantum dot structures has advantages in optical applications due to their sharp delta-like density of states and the reduced intersubband relaxation times [5-8

J. Liu, Y. Bai, and G. Xiong, “Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well,” Physica E 23, 70–74 (2004). [CrossRef]

]. According to traditional quantum size effect, operating in long-IR wavelengths and enhancing the optical nonlinear properties require large sizes of quantum dot [9

X. Zhang, G. Xiong, and X. Feng, “Well Width-dependent Third-order Optical Nonlinearities of a ZnS/CdSe Cylindrical Quantum Dot Quantum Well,” Physica E 33, 120–124 (2006). [CrossRef]

] which leads to low sheet density of quantum dots in layered optoelectronic devices. On the other hand, the absorption peak weakens when the resonant frequency is shifted to lower energies (long wavelengths). It is obvious that these problems degrade device performance in long wavelength regime [10

V. Ryzhii, I. Khmyrova, M. Ryzhii, and V. Mitin, “Comparison of dark current, responsivity and detectivity in different intersubband infrared photodetectors,” Semicond. Sci. Technol. 19, 8–16 (2004). [CrossRef]

]. So it will be interesting to obtain long wavelength transition resonances, enhancing the nonlinear properties and increasing the absorption in lower energies without increasing the size of the quantum structure. In order to reach to all of the mentioned goals, we introduce a defect in center of quantum dot in this paper. The proposed idea is applied to IR photodetectors. The introduced idea shows that IR photodetector can be operated in room and higher temperatures. Higher optical nonlinearity is another important feature of the proposed idea. In this work the introduced idea is evaluated carefully. For this purpose quantum dot structure is presented in section 2. Simulation results and discussion is presented in section 3. Finally the paper ends with a short conclusion.

2. Quantum dot structure

Figure 1 shows the proposed centered defect quantum dot structures. The introduced defect is illustrated obviously in center of the quantum dot. The Spherical Centered Defect Quantum Dot (SCDQD) structure [11

A. Rostami and H. Rasooli Saghai, “A novel proposal for ultra-high optical nonlinearity in GaN/AlGaN spherical centered defect quantum dot (SCDQD),” Microelectron. J. 38, 342–351 (2007). [CrossRef]

] (Fig. 1(a)) is considered for analytical investigation (effective mass Schrödinger equation) and the Centered Defect Quantum Box (CDQB) structure [12

A. Rostami, H. Rasooli Saghai, and H. Baghban, “A Proposal for Enhancement of Optical Nonlinearity in GaN/AlGaN Centered Defect Quantum Box (CDQB) Nanocrystal,” Submitted to Solid state J. (2007).

,13

A. Rostami, H. Rasooli Saghai, and H. Baghban, “A Proposal for Enhancement of Absorption Coefficient and Electroabsorption properties in GaN/AlGaN Centered Defect Quantum Box (CDQB) Nanocrystal,” Submitted to Physica B J. (2007).

] (Fig. 1(b)) is proposed for numerical simulation (self-consistent solution of Schrödinger-Poisson equations) to study the off-centered defect. Ultrafast optical modulation and broad operating range of wavelengths (large conduction band offset) are available in GaN-based structures. Also AlGaN withstands high power optical excitation and high temperature operation [14

N. Suzuki, N. Iizuka, and K. Kaneko, “Simulation of Ultrafast GaN /AlN Intersubband Optical Switches,” IEICE Trans. Electron. E88-C, 342–348 (2005). [CrossRef]

]. The material parameters for AlGaN/GaN are taken from refs [15-17

A. Asgari, M. Kalafi, and L. Faraone, “The Effects of GaN Capping Layer Thickness on Two-dimensional Electron Mobility in GaN/AlGaN/GaN Heterostructures,” Physica E 25, 431–437 (2005). [CrossRef]

].

Fig. 1. (a) SCDQD structure and related spatial potential. (b) CDQB structure.

In order to calculate the eigenstates and wave functions and related quantities, we start by considering the Schrödinger equation in the slowly varying envelope approximation in three dimensions [18

P. Harrison, Quantum Wells, Wires and Dots (John Wiley, 2005). [CrossRef]

]:

{ − ħ2 2 mi* ∇ x,y,z2+ Vi (x,y,z)}ψ (x,y,z)=Eψ (x,y,z)
(1)

where, mi*= { md* for defect region mw* for well region mb* for barrier region , Vi (x,y,z) and ψ(x,y,z) are effective mass,

overall potential distribution and the slowly varying envelope in different regions respectively. The Poisson equation is formulated as:

εi* ∇ x,y,z2Φ (x,y,z)= −e [ ND+ (x,y,z)−n (x,y,z)]
(2)

where, εi = { εd* for defect region εw* for well region εb* for barrier region , Φ(x,y,z), e, N+ D (x,y,z)and n(x,y,z) are

effective dielectric constant, electrostatic potential, electron charge, ionized donor distribution and electron distribution respectively. The first coupling term between (1) and (2) is the overall potential:

Vi (x,y,z)= E Ci −e Φi (x,y,z)
(3)

where E Ci = { E Cd for defect region 0 for well region E Cb for barrier region represents the conduction-band profile given by the

material composition in different regions. The second coupling term is the electron concentration n(x,y,z), which is calculated from the envelope function Φ and the Fermi level EF [19

P. K. Basu, Theory of Optical Processes in Semiconductors (Clarendon Press, Oxford, 1997).

]:

n (x,y,z)=2 ∑k ∣ ψk (x,y,z)∣2 { 1+ exp⁡ [ Ek− EF] KBT} −1
(4)

where, KBT is thermal potential energy. The summation over k represents the summation over all eigenstates. Equilibrium conditions require choosing the Fermi level appropriate to allow that:

∫ −∞ +∞ ND+dν= ∫ −∞ +∞ndν
(5)

For quantum box structure (Fig. 1(b)), the above equations are solved self-consistently and for spherical quantum dot (Fig. 1(a)) analytical solutions are obtained as:

ψ n ℓm= R n ℓ (r) Y ℓm (θ,ϕ),
(6)

Case-1: E<V01

R= { [ C1 iℓ ( κ1r)] 2π 0< r<a [ C2 jℓ ( κ2r)+ C3 nℓ ( κ2r)] 2π a< r<b [ C4 kℓ ( κ3r)] π2   b<r where { κ1= 2 m1* ( V01−E) ħ2 0< r<a κ2= 2 m2*E ħ2 a< r<b κ3= 2 m3* ( V02−E) ħ2 b<r

Case-2: E>V01

R= { [ C1 jℓ ( κ1′r)] 2π 0< r<a [ C2 jℓ ( κ2r)+ C3 nℓ ( κ2r)] 2π a< r<b , where κ1′= 2 m1* ( E− V01) ħ2 [ C4 kℓ ( κ3r)] π2 b<r

After calculating the eigenstates and wave functions, the second-order, third-order nonlinear susceptibilities and linear absorption coefficient, α(ω), for the intersublevel transitions can be clearly calculated by the density matrix approach as [20-25

M. G. Barseghyan and A. A. Kirakosyan, “Light absorption by a two-dimensional quantum dot superlattice,” Physica E 27, 474–480 (2005). [CrossRef]

]:

χ (2)= Nd e3 ∣ dij∣3 ε ħ2 [ 1 ( ω− ωij−i γij)× (2 ω−2 ωij−i γij)]
(7)
χ (3) ( − 2 ω1+ ω2; ω1,− ω2)= −2i Nd q4 ∣ dij∣4 ε0 ħ3 [ 1 [ i ( ω0−2 ω1+ ω2)+ γij] [ i ( ω2− ω1)+ γij]]×

[ 1 i ( ω0− ω1)+ γij+ 1 i ( ω2− ω0)+ γij],
(8)
α (ω)= 4πω e2 Vo ħc ε0 εr ∑ i,j ∣ dij∣2× { f ( Ei)−f ( Ej)}× γij γij2+ ( ω− ωij)2,
(9)

where Nd, ω0, ω e, V0, c, ε0, εr, |dij|, γij (1/τij), ωij are carrier density, resonance frequency between first excited and ground states, photon frequency, electron charge, volume of quantum dot, speed of light, permittivity of vacuum, relative permittivity of semiconductor, dipole transition matrix element (dij=〈ψj|r|ψi 〉 and the parameter r is set along the incident light polarization), relaxation rate (inverse of relaxation time), and transition frequency (resonance frequency between two electronic states) respectively. The expression {f(Ei)-f(Ej)}denotes the Fermi difference of initial and final states. To precisely determine the Fermi energy level, all of the energy levels within the dot should be included. In above equation Lorentzian broadening is considered [21

N. Peyghambarian, S. W. Koch, and A. Mysyrowicz, Introduction to Semiconductor Optics, (Prentice Hall, 1993).

,26

Y. C. Chua, E. A. Decuir, Jr., B. S. Passmore, K. H. Sharif, M. O. Manasreha, Z. M. Wang, and G. J. Salamo, “Tuning In0.3Ga0.7As/GaAs multiple quantum dots for long-wavelength infrared detectors,” Appl. Phys. Lett. 85, 1003–1005 (2004). [CrossRef]

]. For calculating the third-order susceptibilities of quadratic electro optic effect (QEOE) and third harmonic generation (THG), we take ω1=0, ω2=-ω and ω1=-ω2=ω in Eq. (8), respectively. The parameters of the considered material for the proposed quantum dot are given in Table1.

Table 1.  Material parameters [15

A. Asgari, M. Kalafi, and L. Faraone, “The Effects of GaN Capping Layer Thickness on Two-dimensional Electron Mobility in GaN/AlGaN/GaN Heterostructures,” Physica E 25, 431–437 (2005). [CrossRef]

, 27

K. X. Guo and Y. B. Yu, “Nonlinear Optical Susceptibilities in Si/SiO2 Parabolic Quantum Dots,” Chin. J. Phys. 43, 932–940 (2005).

, 28

J. Liu, Y. Bai, and G. Xiong, “Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well,” Physica E 23, 70–74 (2004). [CrossRef]

]
Alx Ga1-xN ParametersUnitValue
Electron effective mass (m*)m0 0.252x+0.228
Band gap (Eg(x))eV6.13x+(1-x)×3.42-x(1-x)
Band offset (ΔEC(x))eV0.7×[Eg(x)-Eg(0)]
Typical Relaxation constant (ħΓ)meV0.3
Barrier density of carriers (N)m−3 1×1024
Well density of carriers (N)m−3 1×1021
Defect density of carriers (N)m−3 1×1021
Relative Dielectric Constant (εr)-8.5x+10.4(1-x)

3. Simulations and results

Figure 2 illustrates simulated results illustrating performance of the proposed new structure. With increasing defect size the energy levels are increased but the difference between levels is decreased (Fig. 2(a)). Since the ground state is affected more than the first excited state so difference of energy levels is decreased and this is considerable especially in higher mole fractions of defect material. Also, defect size increasing pushes the wave functions to the space between defect and barrier (Fig. 2(b)). As it is seen, increasing the defect size and also defect height increase the dipole transition matrix element (Fig. 2(c)). The decrease of matrix element for larger defect sizes is due to tunneling leakage of the wave functions to barrier and defect. So, there is an optimum value of defect size corresponds to maximum matrix element. The maximum range of variation achieved for the dipole transition matrix element is (4.5 – 10 nm).

Fig. 2. (a) Energy levels (ground and first excited states) vs. defect size (A°). (b) Wave functions vs. dot size (A°) with different defect sizes. (c) Dipole transition matrix element vs. defect size with different defect mole fractions (b=75 A°, xb=0.35) for SCDQD structure.

Variation of defect size on intersublevel second-order, quadratic electro optic effect (QEOE) and third harmonic generation (THG) nonlinear optical susceptibilities is studied and illustrated in Fig. 3 for SCDQD structure as functions of pump photon energy. With increasing the defect size, the peak of optical susceptibilities increase due to increasing the matrix element and a red shift occurs. So, with control of the defect size, the resonance frequency and amplitude of the nonlinear optical susceptibilities can be managed. The maximum range of variation achieved for second order, QEOE and THG optical nonlinear susceptibilities in SCDQD structure are (10−4~10−2 m.V−1), (10−12~10−9 m2/V2) and (10−11~10−9 m2/V2) respectively. It is clear that there is a considerable enhancement in second and third order susceptibilities, (1~2) and (2~5) order of magnitudes respectively as compared with traditional structures.

Fig. 3. (a) Second-order nonlinear optical susceptibility. (b) Third order susceptibility of QEOE (m2/V2). (c) Third order susceptibility of THG (m2/V2) vs. pump photon energy with different defect size (b=75 A°, xb=0.35, xd=0.1, ħΓ=0.3 me V) for SCDQD structure.

Effect of defect parameters on the electroabsorption properties and absorption coefficient of CDQB structure are investigated and illustrated in Fig. 4. In the simulated result, the direction of external filed has been considered parallel with the direction of incident light polarization. Figures 4(a), 4(b) and 4(c) describe the energy levels, dipole matrix element, Fermi difference and the absorption coefficient in the presence of external electric field. By increasing the external field, energy of the ground state decreases somewhat more than first excited state and thus the energy difference between these levels is increased. This causes a blue-shift in the absorption spectra. Based on the energy levels characteristic, the probability of electron in the ground state is increased more than first excited state, which leads to increase in Fermi difference. In order to explain the variation of absorption peak, one should consider the competition between resonant frequencies (increases with applied electric field), dipole matrix element (decreases with applied electric field) and Fermi difference (increases with applied field). In Fig. 4(d) it is shown that with increasing the defect size, the absorption peak is increased and a red shift observed. Based on the parameters used in the presented calculation the maximum enhancement of the absorption coefficient is (4.7×102~3.8×104 cm−1). It is considerable that the calculated absorption peak increases despite of shifting to lower energies and resonant frequencies.

Fig. 4. (a) Energy levels. (b) Dipole matrix element & Fermi difference vs. external voltage. (c) Absorption coefficient (ground state → first excited state) vs. pump photon energy for different external voltages (D=10A°) (d) Absorption coefficient (ground state → third excited state) vs. pump photon energy (Barrier=120 A°,Well =80 A°, xb=0.45, xd= 0.1) for CDQB structure.

In this part, we investigate SCDQD as a basic cell of THZ-IR photodetector [29

H. Rasooli Saghai, N. Sadoogi, and A. Rostami, “Ultra-High Detectivity Room Temperature THZ IRPhotodetector Based on Resonant Tunneling Spherical Centered Defect Quantum Dot (RT-SCDQD),” Submitted to Solid state J. (2007).

]. It should mention that there are other proposals for photodetectors in infrared and visible ranges [30-32

S. A. Mcdonald, G. Konstantatos, S. Zhang, P. W. Cyr, E. J. D. Klem, L. Levina, and E. H. Sargent, “Solution-processed PbS quantum dot infrared photodetectors and photovoltaics,” Nature Materials , 4, 138–142 (2005). [CrossRef] [PubMed]

]. The proposed structure in this paper (inset of Fig. 5(b)) contains a SCDQD which is followed by a resonant tunneling double barrier (RT). The proposed double barrier parameters are designed so that the resonance energy to be close to first excited state of the quantum dot. We use AlGaN to increase barriers height for decreasing thermionic emission term in dark current. Vertical transport scheme is considered for the QDIP based on RT-SCDQD cells. Detectivity ( D*= Rpo AeffΔf in where R°P, Aeff, Δf and in are the peak responsivity in QDIP, absorption effective cross-section area, bandwidth and photoconductor current noise respectively) of different structures for evaluation of capability of the proposed system with and without defect and resonant tunneling double barrier is calculated and illustrated in Fig. 5(a). The total noise for a photodetector can be expressed as I2 N =(4IeG+4kT/R).Δf where the first term indicates generation-recombination (shot) noise and the second term stands for the Johnson (thermal) noise. The Johnson noise is not included in the calculation, since it is generally much less than the shot noise [33-35

K. K. Choi, The Physics of Quantum Well Infrared Photodetectors (World Scientific, 1997). [CrossRef]

]. It is shown that the proposed complete structure A (RT-SCDQD based THZ-IR photodetector) considerably has large detectivity and narrow spectra compared with other cases. The reported ultra high value of detectivity (5×1016 cmHz1/2/W at 83°K at 83µm) is related to two basic effects. One is responsivity which increases due to enhancement of the quantum efficiency in SCDQD compared with other quantum dots without defect. Including the defect in quantum dot increases the dipole transition matrix element (Fig. 2(c)) and so increases the absorption coefficient considerably (1.05×106~7.33×106 m−1 at 83µm) (Fig. 5(c)). Therefore the quantum efficiency in SCDQD structure enhances. Second effect relates to decrease of the dark current in the proposed structure. Decreasing the dark current in the proposed structure is because of the following reasons:

  1. Increasing the barrier height increases electron thermal activation energy, concluding to decrease the thermionic term in the dark current (direct thermal excitation of electrons from ground state to continuum). This subject may be introduce some difficulty in electron collection in photodetector, which is removed using double barrier element that resonances with first excited state of dot.
  2. Using double barrier element in the proposed system, also introduces ultra low sequential ground state dark current.

Finally, the proposed photodetector is examined at room temperature (Fig. 5(b)). It is observed that the calculated result shows interesting value which illustrates capability for working at room temperature (2.25×109 cmHZ1/2/W at 83µm). This is so interesting and well large value compared previous reported results. It can be understood that in this structure we decreased considerably the dark current owing to tuning the intersubband transition to mid conduction band offset to decrease thermal effect (variation of Fermi level and thermionic emission from level to continuum band) and finally extracting and collecting the electrons through resonant tunneling double barrier structure. In Table 2 a comparison between detectivity of the proposed RT-SCDQD based THZ-IR photodetector and some experimental reported results are presented.

Fig. 5. (a) Detectivity of different photodetector structures (with defect and double barrier (A: a=55 A°, b=70 A°, c=90 A°, d=110 A°, Lspacer=130 A°, xb=0.3, xd=0.1, Vext=2V), with defect without double barrier (B) and without defect without double barrier (C)) at 83 °K, (b) Detectivity of RT-SCDQD based THZ-IR photodetector at room temperature and (c) Absorption coefficient (ground state → first excited state) (xb=0.3, xd=0.1) vs. pump photon energy. Inset figure in part (b), shows 3-D scheme and potential distribution of RT-SCDQD.
Table 2.  Comparison between detectivity of proposed structure and some experimental reported results
ReferenceTemperature (k°)Wavelength (µm)Detectivity (cmHz1/2/W)
RT-SCDQD based
THZ-IR photodetector		83835×1016
RT-SCDQD based
THZ-IR photodetector		300832.25×109
Ref. 36

X. Su, S. Chakrabarti, P. Bhattacharya, G. Ariyawansa, and A. G. U. Perera, “A Resonant Tunneling Quantum-Dot Infrared Photodetector,” IEEE J. Quantum Electron. 41, 974–979 (2005). [CrossRef]

300178.6×106
Ref. 37

X. H. Su, J. Yang, P. Bhattacharya, G. Ariyawansa, and A. G. Perera, “Terahertz detection with tunneling quantum dot intersublevel photodetector,” Appl. Phys. Lett. 89, 031117-1–031117-3 (2006). [CrossRef]

4.6501×108
Ref. 38

G. Huang, J. Yang, P. Bhattacharya, G. Ariyawansa, and A. G. Perera, “A multicolor quantum dot intersublevel detector with photoresponse in the terahertz range,” Appl. Phys. Lett. 92, 011117 (2008). [CrossRef]

15020-552×107
Ref. 39

A. B. Weerasekara, M. B. M. Rinzan, S. G. Matsik, A. G. U. Perera, M. Buchanan, H. C. Liu, G. von Winckel, A. Stintz, and S. Krishna, “n-Type GaAs/AlAs heterostructure detector with a 3.2 THz threshold frequency,” Opt. Lett. 32, 1335–1337 (2007). [CrossRef] [PubMed]

6-25935.5×108

In the following effect of off-centered defect on the behavior of carrier sheet density of ground state and third order susceptibilities are discussed. In order to clarify the behavior of the wave functions in presence of the defect, the cross section of the wave functions is considered as carrier sheet density (|Ψ(x, y, z)|2 for a specific x-plane). Figure 6(a) illustrates the carrier density of ground state for four different defect sizes (D=0, 10, 20, 40 A° from left to right and up to down). Higher intensities in this figure show higher magnitudes of the carrier densities. It is shown that with increasing the defect size, the intensity of the carrier sheet density in the defect location is decreased and so the carrier sheet density is much confined between defect and barrier space. Figure 6(b) shows the carrier densities of ground states for different defect deviation from center position (Dev=0, 5, 10, 15 A° from left to right and up to down respectively). In the first part of Fig. 6(b), the defect is obviously on-center. By moving the defect along the diagonal of the box (other parts of Fig 6(b)), the intensity of carrier densities is pushed to opposite direction of moving. Also a small blue shift and weak amplitude variation (~1×10−14) is observable in the third-order susceptibilities (Figs. 6(c) and 6(d)). So it can be said that, the third-order nonlinear susceptibilities are almost insensitive to the position of defect. It is approximately not important where the wave functions are confined inside the well. The important fact is the presence of the defect.

Fig. 6. Carrier sheet density of ground state, (a) with different central defect sizes (B=120 A°,W=80 A°, xb=0.35, xd=0.27). (b) with different deviations from center position. (c) QEOE (m2/V2). (d) THG (m2/V2) vs. pump photon energy with different deviation from center position (Barrier=120 A°, Well=80 A°, D=10 A°, xb=0.35, xd=0.27) for CDQB structure.

In this section different aspect of the proposed structure has been investigated carefully. It was shown that the proposed quantum dot structure have so interesting optical properties for photonic applications.

4. Summery

The proposed novel structures (SCDQD and CDQB) of GaN-AlGaN quantum dots exhibit enhanced nonlinear optical susceptibilities, absorption coefficient and electroabsorption properties in smaller sizes suitable for a basic cell of high performance optoelectronic devices operating in long wavelengths. It was shown that the proposed structure is excellent for optoelectronic basic cell for infrared applications such as photodetectors and THZ applications.

References

1.

S. Ghosh, A. S. Lenihan, M. V. G. Dutt, O. Qasaimeh, D. G. Steel, and P. Bhattacharya, “Nonlinear Optical and Electro-optic Properties of InAs/GaAs Self-organized Quantum Dots,” J. Vac. Sci. Technol. B. 19, 1455–1458 (2001). [CrossRef]

2.

E. Rosencher, P. Bois, J. Nagle, and S. Delaitre, “Second Harmonic Generation by Intersubband Transitions in Compositionally Asymmetrical MQWs,” Electron. Lett. 25, 1063–1065 (1989). [CrossRef]

3.

S. Banerjee and K. A. Shore, “MIR and NIR Nonlinear Optical Processing using Intersubband χ (3) in triple Quantum Well Structures,” Inst. Phys. Publish. UK. 655–660l (2003).

4.

T. Brunhes, P. Boucaud, S. Sauvage, F. Glotin, R. Prazeres, J. -M. Ortega, A. Lemaitre, and J.-M. Gerard, “Midinfrared Second-harmonic Generation in P-type InAs/GaAs Self-assembled Quantum Dots,” Appl. Phys. Lett. 75, 835–837 (1999). [CrossRef]

5.

J. Liu, Y. Bai, and G. Xiong, “Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well,” Physica E 23, 70–74 (2004). [CrossRef]

6.

S. Sauvage, P. Boucaud, T. Brunhes, F. Glotin, R. Prazeres, J. M. Ortega, and J. M. Gerard, “Second-harmonic Generation Resonant with S-P Transition in InAs/GaAs Self-assembled Quantum Dots,” Phys. Rev. B 63, 113312_1–113312_4 (2001). [CrossRef]

7.

K. W. Berryman, S. A. Lyon, and M. Segev, “Mid-infrared photoconductivity in InAs quantum dots,” Appl. Phys. Lett. 70, 1861–1863 (1997). [CrossRef]

8.

J. L. Liu, W. G. Wu, A. Balandin, G. L. Jin, and K. L. Wang, “Intersubband absorption in boron-doped multiple Ge quantum dots,” Appl. Phys. Lett. 74, 185–187 (1999). [CrossRef]

9.

X. Zhang, G. Xiong, and X. Feng, “Well Width-dependent Third-order Optical Nonlinearities of a ZnS/CdSe Cylindrical Quantum Dot Quantum Well,” Physica E 33, 120–124 (2006). [CrossRef]

10.

V. Ryzhii, I. Khmyrova, M. Ryzhii, and V. Mitin, “Comparison of dark current, responsivity and detectivity in different intersubband infrared photodetectors,” Semicond. Sci. Technol. 19, 8–16 (2004). [CrossRef]

11.

A. Rostami and H. Rasooli Saghai, “A novel proposal for ultra-high optical nonlinearity in GaN/AlGaN spherical centered defect quantum dot (SCDQD),” Microelectron. J. 38, 342–351 (2007). [CrossRef]

12.

A. Rostami, H. Rasooli Saghai, and H. Baghban, “A Proposal for Enhancement of Optical Nonlinearity in GaN/AlGaN Centered Defect Quantum Box (CDQB) Nanocrystal,” Submitted to Solid state J. (2007).

13.

A. Rostami, H. Rasooli Saghai, and H. Baghban, “A Proposal for Enhancement of Absorption Coefficient and Electroabsorption properties in GaN/AlGaN Centered Defect Quantum Box (CDQB) Nanocrystal,” Submitted to Physica B J. (2007).

14.

N. Suzuki, N. Iizuka, and K. Kaneko, “Simulation of Ultrafast GaN /AlN Intersubband Optical Switches,” IEICE Trans. Electron. E88-C, 342–348 (2005). [CrossRef]

15.

A. Asgari, M. Kalafi, and L. Faraone, “The Effects of GaN Capping Layer Thickness on Two-dimensional Electron Mobility in GaN/AlGaN/GaN Heterostructures,” Physica E 25, 431–437 (2005). [CrossRef]

16.

K. X. Guo and Y. B. Yu, “Nonlinear Optical Susceptibilities in Si/SiO2 Parabolic Quantum Dots,” Chin. J. Phys. 43, 932–940 (2005).

17.

J. Liu, Y. Bai, and G. Xiong, “Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well,” Physica E 23, 70–74 (2004). [CrossRef]

18.

P. Harrison, Quantum Wells, Wires and Dots (John Wiley, 2005). [CrossRef]

19.

P. K. Basu, Theory of Optical Processes in Semiconductors (Clarendon Press, Oxford, 1997).

20.

M. G. Barseghyan and A. A. Kirakosyan, “Light absorption by a two-dimensional quantum dot superlattice,” Physica E 27, 474–480 (2005). [CrossRef]

21.

N. Peyghambarian, S. W. Koch, and A. Mysyrowicz, Introduction to Semiconductor Optics, (Prentice Hall, 1993).

22.

Y. R. Shen, The Principles of Nonlinear Optics (John Wiley, 2003).

23.

R. W. Boyd, Nonlinear Optics (Academic Press, 1992).

24.

B. Kochman, A. D. Stiff-Roberts, S. Chakrabarti, J. D. Phillips, S. Krishna, J. Singh, and P. Bhattacharya,“Absorption, Carrier Lifetime, and Gain in InAs-GaAs Quantum-Dot Infrared Photodetectors,” IEEE J. Quantum Electron. 39, 459–467 (2003). [CrossRef]

25.

K. Chang and J. B. Xia, “Spatially Separated Excitons in Quantum-Dot Quantum Well Structures,” Phys. Rev. B 57, 9780–9786 (1998). [CrossRef]

26.

Y. C. Chua, E. A. Decuir, Jr., B. S. Passmore, K. H. Sharif, M. O. Manasreha, Z. M. Wang, and G. J. Salamo, “Tuning In0.3Ga0.7As/GaAs multiple quantum dots for long-wavelength infrared detectors,” Appl. Phys. Lett. 85, 1003–1005 (2004). [CrossRef]

27.

K. X. Guo and Y. B. Yu, “Nonlinear Optical Susceptibilities in Si/SiO2 Parabolic Quantum Dots,” Chin. J. Phys. 43, 932–940 (2005).

28.

J. Liu, Y. Bai, and G. Xiong, “Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well,” Physica E 23, 70–74 (2004). [CrossRef]

29.

H. Rasooli Saghai, N. Sadoogi, and A. Rostami, “Ultra-High Detectivity Room Temperature THZ IRPhotodetector Based on Resonant Tunneling Spherical Centered Defect Quantum Dot (RT-SCDQD),” Submitted to Solid state J. (2007).

30.

S. A. Mcdonald, G. Konstantatos, S. Zhang, P. W. Cyr, E. J. D. Klem, L. Levina, and E. H. Sargent, “Solution-processed PbS quantum dot infrared photodetectors and photovoltaics,” Nature Materials , 4, 138–142 (2005). [CrossRef] [PubMed]

31.

G. Konstantatos, I. Howard, A. Fischer, S. Hoogland, J. Clifford, E. Klem, L. Levina, and E. H. sergeant, “Ultrasensitive solution-cast quantum dot photodetectors,” Nature , 442, 180–183 (2006). [CrossRef] [PubMed]

32.

G. Konstantatos, J. Clifford, L. Levina, and E. H. Sargent, “Sensitive solution-processed visiblewavelength photodetectors,” Nature photonics , 1, 531–534 (2007). [CrossRef]

33.

K. K. Choi, The Physics of Quantum Well Infrared Photodetectors (World Scientific, 1997). [CrossRef]

34.

B. F. Levine, “Quantum -well infrared photodetectors,” J. Appl. Phys. 74, R1–R81 (1993). [CrossRef]

35.

T. Steiner, Semiconductor Nanostructures for Optoelectronic Applications (Artech House, Inc. Boston, London, 2004).

36.

X. Su, S. Chakrabarti, P. Bhattacharya, G. Ariyawansa, and A. G. U. Perera, “A Resonant Tunneling Quantum-Dot Infrared Photodetector,” IEEE J. Quantum Electron. 41, 974–979 (2005). [CrossRef]

37.

X. H. Su, J. Yang, P. Bhattacharya, G. Ariyawansa, and A. G. Perera, “Terahertz detection with tunneling quantum dot intersublevel photodetector,” Appl. Phys. Lett. 89, 031117-1–031117-3 (2006). [CrossRef]

38.

G. Huang, J. Yang, P. Bhattacharya, G. Ariyawansa, and A. G. Perera, “A multicolor quantum dot intersublevel detector with photoresponse in the terahertz range,” Appl. Phys. Lett. 92, 011117 (2008). [CrossRef]

39.

A. B. Weerasekara, M. B. M. Rinzan, S. G. Matsik, A. G. U. Perera, M. Buchanan, H. C. Liu, G. von Winckel, A. Stintz, and S. Krishna, “n-Type GaAs/AlAs heterostructure detector with a 3.2 THz threshold frequency,” Opt. Lett. 32, 1335–1337 (2007). [CrossRef] [PubMed]

OCIS Codes
(040.5160) Detectors : Photodetectors
(040.5570) Detectors : Quantum detectors
(190.0190) Nonlinear optics : Nonlinear optics
(250.5590) Optoelectronics : Quantum-well, -wire and -dot devices

ToC Category:
Optoelectronics

History
Original Manuscript: November 13, 2007
Revised Manuscript: January 20, 2008
Manuscript Accepted: January 28, 2008
Published: February 13, 2008

Citation
A. Rostami, H. Rasooli Saghai, N. Sadoogi, and H. Baghban Asghari Nejad, "Proposal for ultra-high performance infrared Quantum Dot," Opt. Express 16, 2752-2763 (2008)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-4-2752


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References

  1. Ghosh, S. , Lenihan, A.S. , Dutt, M.V.G. , Qasaimeh, O. , Steel, D.G. , and Bhattacharya, P.  (2001). Nonlinear Optical and Electro-optic Properties of InAs/GaAs Self-organized Quantum Dots. J. Vac. Sci. Technol. B 19, 1455-1458. [CrossRef]
  2. Rosencher, E. , Bois, P. , Nagle, J. , and Delaitre, S.  (1989). Second Harmonic Generation by Intersubband Transitions in Compositionally Asymmetrical MQWs. Electron. Lett. 25, 1063-1065. [CrossRef]
  3. S. Banerjee, K. A. Shore, "MIR and NIR Nonlinear Optical Processing using Intersubband x(3) in triple Quantum Well Structures," Inst. Phys. Publish. UK. 655-660l (2003).
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  5. Liu, J. , Bai, Y. , and Xiong, G.  (2004). Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well. Physica E (Amsterdam) 23, 70-74. [CrossRef]
  6. S. Sauvage, P. Boucaud, T. Brunhes, F. Glotin, R. Prazeres, J. M. Ortega, J. M. Gerard, "Second-harmonic Generation Resonant with S-P Transition in InAs/GaAs Self-assembled Quantum Dots," Phys. Rev. B 63, 113312_1-113312_4 (2001). [CrossRef]
  7. Berryman, K.W. , Lyon, S.A. , and Segev, M.  (1997). Mid-infrared photoconductivity in InAs quantum dots. Appl. Phys. Lett. 70, 1861-1863. [CrossRef]
  8. Liu, J.L. , Wu, W.G. , Balandin, A. , Jin, G.L. , and Wang, K.L.  (1999). Intersubband absorption in boron-doped multiple Ge quantum dots. Appl. Phys. Lett. 74, 185-187. [CrossRef]
  9. Zhang, X. , Xiong, G. , and Feng, X.  (2006). Well Width-dependent Third-order Optical Nonlinearities of a ZnS/CdSe Cylindrical Quantum Dot Quantum Well. Physica E (Amsterdam) 33, 120-124. [CrossRef]
  10. Ryzhii, V. , Khmyrova, I. , Ryzhii, M. , and Mitin, V.  (2004). Comparison of dark current, responsivity and detectivity in different intersubband infrared photodetectors. Semicond. Sci. Technol. 19, 8-16. [CrossRef]
  11. Rostami, A. , and Rasooli Saghai, H.  (2007). A novel proposal for ultra-high optical nonlinearity in GaN/AlGaN spherical centered defect quantum dot (SCDQD). Microelectron. J. 38, 342-351. [CrossRef]
  12. Rostami, A. , Rasooli Saghai, H. , and Baghban, H.  "A Proposal for Enhancement of Optical Nonlinearity in GaN/AlGaN Centered Defect Quantum Box (CDQB) Nanocrystal," Submitted to Solid state J. (2007).
  13. Rostami, A. , Rasooli Saghai, H. , and Baghban, H.  "A Proposal for Enhancement of Absorption Coefficient and Electroabsorption properties in GaN/AlGaN Centered Defect Quantum Box (CDQB) Nanocrystal," Submitted to Physica B J. (2007).
  14. Suzuki, N. , Iizuka, N. , and Kaneko, K.  (2005). "Simulation of Ultrafast GaN /AlN Intersubband Optical Switches," IEICE Trans. Electron.E 88-C, 342-348. [CrossRef]
  15. Asgari, A. , Kalafi, M. , and Faraone, L.  (2005). The Effects of GaN Capping Layer Thickness on Two-dimensional Electron Mobility in GaN/AlGaN/GaN Heterostructures. Physica E (Amsterdam) 25, 431-437. [CrossRef]
  16. Guo, K.X. , and Yu, Y.B.  (2005). Nonlinear Optical Susceptibilities in Si/SiO2 Parabolic Quantum Dots. Chin. J. Physiol. 43, 932-940.
  17. Liu, J. , Bai, Y. , and Xiong, G.  (2004). Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well. Physica E (Amsterdam) 23, 70-74. [CrossRef]
  18. Harrison, P. Quantum Wells, Wires and Dots (John Wiley, 2005). [CrossRef]
  19. Basu, P.K. Theory of Optical Processes in Semiconductors (Clarendon Press, Oxford, 1997).
  20. Barseghyan, M.G. , and Kirakosyan, A.A.  (2005). Light absorption by a two-dimensional quantum dot superlattice. Physica E (Amsterdam) 27, 474-480. [CrossRef]
  21. Peyghambarian, N. , Koch, S.W. , and Mysyrowicz, A.  Introduction to Semiconductor Optics, (Prentice Hall, 1993).
  22. Shen, Y.R. The Principles of Nonlinear Optics (John Wiley, 2003).
  23. Boyd, R.W. Nonlinear Optics (Academic Press, 1992).
  24. Kochman, B. , Stiff-Roberts, A.D. , Chakrabarti, S. , Phillips, J.D. , Krishna, S. , Singh, J. , and Bhattacharya, P.  (2003). Absorption, Carrier Lifetime, and Gain in InAs-GaAs Quantum-Dot Infrared Photodetectors. IEEE J. Quantum Electron. 39, 459-467. [CrossRef]
  25. Chang, K. , and Xia, J.B.  (1998). Spatially Separated Excitons in Quantum-Dot Quantum Well Structures. Phys. Rev. B 57, 9780-9786. [CrossRef]
  26. Chua, Y.C. , Decuir, E.A. , Jr., Passmore, B.S. , Sharif, K.H. , Manasreha, M.O. , Wang, Z.M. , and Salamo, G.J.  (2004). Tuning In0.3Ga0.7As/GaAs multiple quantum dots for long-wavelength infrared detectors. Appl. Phys. Lett. 85, 1003-1005. [CrossRef]
  27. Guo, K.X. , and Yu, Y.B.  (2005). Nonlinear Optical Susceptibilities in Si/SiO2 Parabolic Quantum Dots. Chin. J. Physiol. 43, 932-940.
  28. Liu, J. , Bai, Y. , and Xiong, G.  (2004). Studies of the Second-order Nonlinear Optical Susceptibilities of GaN/AlGaN Quantum Well. Physica E (Amsterdam) 23, 70-74. [CrossRef]
  29. Rasooli Saghai, H. , Sadoogi, N. , and Rostami, A.  "Ultra-High Detectivity Room Temperature THZ IR-Photodetector Based on Resonant Tunneling Spherical Centered Defect Quantum Dot (RT-SCDQD)," Submitted to Solid state J. (2007).
  30. Mcdonald, S.A. , Konstantatos, G. , Zhang, S. , Cyr, P.W. , Klem, E.J.D. , Levina, L. , and Sargent, E.H.  (2005). Solution-processed PbS quantum dot infrared photodetectors and photovoltaics. Nat. Mater. 4, 138-142. [CrossRef] [PubMed]
  31. G. Konstantatos, I. Howard, A. Fischer, S. Hoogland, J. Clifford, E. Klem, L. Levina and E. H. sergeant, "Ultrasensitive solution-cast quantum dot photodetectors," Nature,  442, 180 - 183 (2006). [CrossRef] [PubMed]
  32. G. Konstantatos, J. Clifford, L. Levina and E. H. Sargent, "Sensitive solution-processed visible-wavelength photodetectors," Nature photonics,  1, 531-534 (2007). [CrossRef]
  33. Choi, K.K. The Physics of Quantum Well Infrared Photodetectors (World Scientific, 1997). [CrossRef]
  34. Levine, B.F.  (1993). Quantum -well infrared photodetectors. J. Appl. Phys. 74, R1-R81. [CrossRef]
  35. Steiner, T. Semiconductor Nanostructures for Optoelectronic Applications (Artech House, Inc. Boston, London, 2004).
  36. Su, X. , Chakrabarti, S. , Bhattacharya, P. , Ariyawansa, G. , and Perera, A.G.U.  (2005). A Resonant Tunneling Quantum-Dot Infrared Photodetector. IEEE J. Quantum Electron. 41, 974-979. [CrossRef]
  37. X. H. Su, J. Yang, P. Bhattacharya, G. Ariyawansa and A. G. Perera, "Terahertz detection with tunneling quantum dot intersublevel photodetector," Appl. Phys. Lett. 89, 031117-1-031117-3 (2006). [CrossRef]
  38. Huang, G. , Yang, J. , Bhattacharya, P. , Ariyawansa, G. , and Perera, A.G.  (2008). A multicolor quantum dot intersublevel detector with photoresponse in the terahertz range. Appl. Phys. Lett. 92, 011117. [CrossRef]
  39. Weerasekara, A.B. , Rinzan, M.B.M. , Matsik, S.G. , Perera, A.G.U. , Buchanan, M. , Liu, H.C. , von Winckel, G. , Stintz, A. , and Krishna, S.  (2007). n-Type GaAs/AlAs heterostructure detector with a 3.2 THz threshold frequency. Opt. Lett. 32, 1335-1337. [CrossRef] [PubMed]

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