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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 4 — Feb. 13, 2012
  • pp: 3932–3940
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Influence of excitation power and temperature on photoluminescence in InGaN/GaN multiple quantum wells

Huining Wang, Ziwu Ji, Shuang Qu, Gang Wang, Yongzhi Jiang, Baoli Liu, Xiangang Xu, and Hirofumi Mino  »View Author Affiliations


Optics Express, Vol. 20, Issue 4, pp. 3932-3940 (2012)
http://dx.doi.org/10.1364/OE.20.003932


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Abstract

Excitation power and temperature dependences of the photoluminescence (PL) spectra are studied in InGaN/GaN multiple quantum wells (MQWs). The excitation power dependences of the PL peak energy and linewidth indicate that the emission process of the MQWs is dominated first by the Coulomb screening effect and then by the localized states filling at low temperature, and that the nonradiative centers are thermally activated in low excitation range at room temperature. The anomalous temperature dependences of the peak energy and linewidth are well explained by the localized carrier hopping and thermalization process, and by the exponentially increased density of states with energy in the band tail. Moreover, it is also found that internal quantum efficiency is related to the mechanism conversion from nonradiative to radiative mechanism, and up to the carriers escaping from localized states.

© 2012 OSA

1. Introduction

InGaN alloys have been attracting much attention as potential materials for the fabrication of high brightness light emitting diodes (LEDs) and continuous wave (cw) blue laser diodes because of the advantage of tuning ability of the alloy bandgap. Understanding the emission mechanism in InGaN multiple quantum well (MQW) structures is a key issue for further developing such optoelectronics devices [1

1. S. Nakamura, S. Pearton, and G. Fasol, The Blue Laser Diode (Springer, Berlin, 2000).

3

3. T. Mukai, H. Narimatsu, and S. Nakamura, “Amber InGaN-based light-emitting diodes operable at high ambient temperatures,” Jpn. J. Appl. Phys. 37(Part 2, No. 5A), L479–L481 (1998). [CrossRef]

]. The widely accepted viewpoint is that the inhomogeneous distribution of indium facilitates high quantum efficiency of nitride-based LEDs in spite of the tremendous density of dislocations of InGaN/GaN MQWs grown on the lattice-mismatched substrates [4

4. S. Chichibu, T. Sota, K. Wada, and S. Nakamura, “Exciton localization in InGaN quantum well devices,” J. Vac. Sci. Technol. B 16(4), 2204–2214 (1998). [CrossRef]

]. The localized excitons within indium-rich regions resulting from partial phase segregation in InGaN alloys are considered to prevent them from reaching nonradiative recombination sites and play an important role for spontaneous emission. However, to our knowledge, the character of carrier motion, and the relevant process of establishing their distribution over the localized states in InGaN remain to be further explored [5

5. G. Sun, G. B. Xu, Y. J. Ding, H. P. Zhao, G. Y. Liu, J. Zhang, and N. Tansu, “Investigation of fast and slow decays in InGaN/GaN quantum wells,” Appl. Phys. Lett. 99(8), 081104 (2011). [CrossRef]

, 6

6. Y. Yamane, K. Fujiwara, and J. K. Sheu, “Largely variable electroluminescence efficiency with current and temperature in a blue (In, Ga)N multiple-quantum-well diode,” Appl. Phys. Lett. 91(7), 073501 (2007). [CrossRef]

].

In this paper, in order to clarify the underlying physics of light emission from InGaN/GaN MQWs, we measured the excitation power (P) and temperature (T) dependences of the photoluminescence (PL) spectra, and revealed the physical mechanism behind by analyzing the emission energy, linewidth, intensity, and internal quantum efficiency (IQE).

2. Experiments

The InGaN/GaN MQWs were grown on a (0001)-oriented sapphire using metalorganic chemical vapor deposition (MOCVD). The precursors of Ga, In, N, and Si were trimethylgallium (TMGa), trimethylindium (TMIn), ammonia (NH3), and silane (SiH4), respectively. The QWs were grown under N2 ambient after a 1.5-μm-thick undoped GaN buffer layer and a 2.5-μm-thick Si-doped GaN layer. The active region consisted of 8 MQWs with 3-nm-thick InGaN wells and 14-nm-thick GaN barriers. The indium content of the active region is about 15%.

For excitation power and temperature dependent PL measurement, the sample was mounted in a closed-cycle He cryostate and the temperature was controlled from 6 to 300 K. A 405 nm cw semiconductor laser was used as an excitation light source with the spot size of ~170 μm, and the excitation power changed from 0.001 to 50 mW. The PL signal from the sample was dispersed by a Jobin-Yven iHR320 monochromator and detected by a thermoelectrical cooled Synapse CCD detector.

3. Results and discussions

Figure 1
Fig. 1 Emission peak energy and full width at half maximum (FWHM) as a function of excitation power for the InGaN/GaN MQWs at 6 K (a) and 300 K (b).
shows the peak energy and linewidth of the spectra as a function of the excitation power at 6 and 300 K. At 6 K, as shown in Fig. 1(a), the peak energy monotonically increases with increasing excitation power. While the linewidth first decreases in the low excitation range of P < 15 mW, and then increases as the excitation power further increased. The behavior of the spectra can be explained as follows. The first is Coulomb screening of quantum-conðned Stark effect (QCSE) resulting from the internal electric field, since increasing photogenerated carrier density weakens the QCSE [7

7. J. Zhang and N. Tansu, “Improvement in spontaneous emission rates for InGaN quantum wells on ternary InGaN substrate for light-emitting diodes,” J. Appl. Phys. 110(11), 113110 (2011). [CrossRef]

], and that results in the increasing of the peak energy with increasing excitation power at P < 15 mW. As the screening effect dominates the emission process, it accompanied a reduction in linewidth [8

8. D. A. B. Miller, D. S. Chemla, T. C. Damen, A. C. Gossard, W. Wiegmann, T. H. Wood, and C. A. Burrus, “Electric field dependence of optical absorption near the band gap of quantum-well structures,” Phys. Rev. B Condens. Matter 32(2), 1043–1060 (1985). [CrossRef] [PubMed]

]. With further increasing excitation power (P > 15 mW), the band-filling effect of high-energetic localized centers resulting from the inhomogeneous distribution of the indium starts interfering and becomes dominant, that also induces a blueshift of the emission energy. But, unlike the effect of QCSE, the effect accompanies the broadening of linewidth.

Figure 2(a)
Fig. 2 Temperature dependence of PL peak energy (a) and FWHM (b) measured at different excitation powers. The temperature Tmin and Tmax, corresponding to the minimum and maximum of the peak energy at different excitation powers, respectively, are shown by the arrow as a guide to the eye. The solid curve is calculated using the band-tail model [Eq. (1)]. The box marks the initial decreasing of the temperature dependent linewidth in the temperature range of T < 40 K.
plots the temperature dependence of the peak energy over a broader excitation power range. The anomalous temperature behavior is clearly observed in the curves measured at P = 0.05 mW. First, it redshifts until a temperature (noted as Tmin) of ~60 K corresponding to a maximum of the localization energy, then, it blueshifts up to the full-delocalization temperature (noted as Tmax) of ~170 K, where it starts redshifting again. The anomalous temperature behavior of the peak energy is S-shaped (decrease-increase-decrease) [9

9. Y.-H. Cho, G. H. Gainer, A. J. Fischer, J. J. Song, S. Keller, U. K. Mishra, and S. P. DenBaars, “‘S-shaped’ temperature-dependent emission shift and carrier dynamics in InGaN/GaN multiple quantum wells,” Appl. Phys. Lett. 73(10), 1370–1372 (1998). [CrossRef]

14

14. K. S. Ramaiah, Y. K. Su, S. J. Chang, C. H. Chen, F. S. Juang, H. P. Liu, and I. G. Chen, “Studies of InGaN/GaN multiquantum-well green-light-emitting diodes grown by metalorganic chemical vapor deposition,” Appl. Phys. Lett. 85(3), 401–403 (2004). [CrossRef]

]. The peculiarity manifests itself also in the temperature dependence of the PL linewidth [Fig. 2(b)]. It decreases slowly until a temperature close to the Tmin. Then it increases significantly up to a temperature slightly higher than the Tmin. Further, it decreases up to a temperature close to the Tmax. Finally, the linewidth increases steadily up to 300 K again. The change of the linewidth shows a W-shaped (decrease-increase-decrease-slowly increase-increase) temperature dependence.

To explain in detail above mentioned the S-shaped (W-shaped) temperature dependent behavior of the peak energy (linewidth) observed at P = 0.05 mW in our present study (Fig. 2), the schematic diagrams indicating the possible mechanism of carriers transferring in the MQWs structure at different temperatures with P = 0.05 mW is shown in Fig. 3
Fig. 3 Schematic diagrams indicating the possible mechanism of carriers transferring in the MQWs structure at different T at P = 0.05 mW. (a)–(d) represent respectively the case of the carriers distribution at lowest T (such as 6 K), Tmin (60 K), a T slightly higher than Tmin, and a T close to Tmax.
. At low temperature of 6 K, carriers are randomly distributed among the potential minima [Fig. 3(a)]. As the temperature increases from 6 K up to Tmin ≈60 K, weakly localized carriers are thermally activated and relax down into other strongly localized states via hopping [15

15. D. Monroe, “Hopping exponential band tails,” Phys. Rev. Lett. 54(2), 146–149 (1985). [CrossRef] [PubMed]

17

17. M. Grünewald, B. Movaghar, B. Pohlmann, and D. Würtz, “Hopping theory of band-tail relaxation in disordered semiconductors,” Phys. Rev. B Condens. Matter 32(12), 8191–8196 (1985). [CrossRef] [PubMed]

] and reach a saturated redistribution [Fig. 3(b)], which results in the initial redshift of the peak energy as large as 18 meV [Fig. 2(a)]. It is consistent with the initial decreasing of the PL linewidth in the temperature range of T ≈6–40 K [Fig. 2(b)]. After 60 K, increasing temperature enable carriers to achieve the thermal equilibrium with the lattice and to occupy higher-energy levels of the localized states [Fig. 3(c)], thus results in the blueshift of the peak energy as large as 33 meV toward the free-exciton ground state up to Tmax ≈170 K [Fig. 2(a)]. Accordingly, the rapid increase of the linewidth in T ≈40–70 K represents a crossover from nonthermalized to thermalized energy distribution of localized excitons [Fig. 2(b)] [18

18. K. Kazlauskas, G. Tamulaitis, A. Žukauskas, M. A. Khan, J. W. Yang, J. Zhang, G. Simin, M. S. Shur, and R. Gaska, “Double-scaled potential profile in a group-III nitride alloy revealed by Monte Carlo simulation of exciton hopping,” Appl. Phys. Lett. 83(18), 3722–3724 (2003). [CrossRef]

, 19

19. K. Kazlauskas, G. Tamulaitis, P. Pobedinskas, A. Žukauskas, M. Springis, C.-F. Huang, Y.-C. Cheng, and C. C. Yang, “Exciton hopping in InxGa1−xN multiple quantum wells,” Phys. Rev. B 71(8), 085306 (2005). [CrossRef]

]. A quick decrease of the linewidth in T ≈70–110 K as shown in Fig. 2(b), is explained as that when further increasing temperature above 70 K, even the most localized carriers become progressively mobile. Therefore the carrier distribution narrows [Fig. 3(d)], and the linewidth decreases. After T ≈110 K, the role of the regular thermalization of carriers starts to become more and more important, which results in the linewidth increase at a lower rate up to the full-delocalization temperature of Tmax ≈170 K [Fig. 2(b)]. It is consistent with the slow increase of the peak energy in the temperature range [Fig. 2(a)]. Finally, the peak energy decreases and the linewidth increases markedly up to 300 K, in agreement with a regular thermalization of the carriers.

The temperature-indueced blueshit of the peak energy can be described by the band-tail model [20

20. P. G. Eliseev, P. Perlin, J. Lee, and M. Osiński, “Blue temperature-induced shift and band-tail emission in InGaN-based light sources,” Appl. Phys. Lett. 71(5), 569–571 (1997). [CrossRef]

, 21

21. P. G. Eliseev, “The red σ2/kT spectral shift in partially disordered semiconductors,” J. Appl. Phys. 93(9), 5404–5415 (2003). [CrossRef]

]:
E(T)=Eg(0)αT2T+βσ2kBT
(1)
where E(T) is the emission energy at T, Eg(0) the energy gap at 0 K, and α and β are Varshni coefficients. The third term comes from the localization effect, in which σ indicates the degree of localization effect, i.e., the large value of σ means a strong localization effect, and kB is the Boltzmann constant. One of the fitting curves made by Eq. (1) is shown in Fig. 2(a) with the following parameters: Eg(0) = 2.72 eV, α = 0.77 meV/K, β = 1000 K, σ = 23.34 meV, and it fits well with our experimental data in the temperature range of 80–300 K. Through fitting [Fig. 2(a)], the values of σ obtained at various excitation powers, as a function of the excitation power, are plotted in Fig. 4(a)
Fig. 4 The values of σ (a), Tmin and Tmax (b) obtained at various excitation powers [see Fig. 2(a)], as a function of the excitation power.
. The decreasing trend of the parameter σ as a function of the excitation power implies the reduced localized effect. As a result, the temperature dependent redshift or blueshift of the peak energy become less prominent with increasing excitation power, correspondingly, the temperature behavior of the peak energy gradually evolves from the S-shaped temperature dependence into a weak S-shaped, and until into an inverted V-shaped temperature dependence [Fig. 2(a)]. While the temperature dependence of the linewidth, as a function of the excitation power, also gradually evolves from the W-shaped temperature dependence into a weak W-shaped, and until into a monotonically increased temperature dependence [Fig. 2(b)]. Although beyond the scope of our study in present work, it can be expected that when the excitation power is large enough, the localization effect will completely disappear, and the temperature behavior of the peak energy will closely follow Varshni law. Moreover, as seen from Fig. 2, as the excitation power increases the band energy blueshifts, corresponding to this process, the linewidth first decreases (P < 15 mW) and then increases (P > 15 mW) at low temperatures, which is attributed to the coulomb screening of the QCSE and the band-filling of the localized states as discussed in Fig. 1. At the same time, both the temperatures Tmin and the Tmax decrease, reflecting the reduced localization effect. The values of the Tmin and Tmax, as a function of the excitation power, are shown in Fig. 4(b).

Figure 5(a)
Fig. 5 Internal quantum efficiency (a) and integrated PL intensity at 6 and 300 K (b) of MQWs as a function of the excitation power.
shows the IQE of the InGaN/GaN MQWs as a function of the excitation power. Here, the IQE is defined as the ratio of the integrated PL intensity at 300 K and 6 K. One can clearly see that the IQE increases markedly in the excitation range of about P < 15 mW, then increases at a lower rate, and finally shows an approximatively saturated tendencywith further increasing excitation power (P > 15 mW). In other words, the increase rate of the IQE gradually decreases with excitation power in our measured range. Now we discuss the mechanism responsible for the dependence of the IQE on the excitation power.

Above mentioned results indicate that though carrier localization is an important aspect in understanding the radiative recombination and improving the IQE in the InGaN QW, the existence of the internal electric fields (i.e., polarization fields) leading to charge separation issues and nonradiative centers are also important limitation in achieving large spontaneous emission rate and high IQE QW active region. Therefore, to achieve a high IQE for InGaN QWs based LEDs, various methods are being pursued by many researchers [25

25. H. P. Zhao, G. Y. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011). [CrossRef] [PubMed]

31

31. Y.-J. Lee, H.-C. Kuo, T.-C. Lu, S.-C. Wang, K. W. Ng, K. M. Lau, Z.-P. Yang, A. S.-P. Chang, and S.-Y. Lin, “Study of GaN-based light-emitting diodes grown on chemical wet-etching-patterned sapphire substrate with V-shaped pits roughening surfaces,” J. Lightwave Technol. 26(11), 1455–1463 (2008). [CrossRef]

], such as, the use of the staggered InGaN QW and InGaN-delta-InN QW both with improved electron-hole wavefuctions overlap design for the enhancement of its radiative recombination rate [28

28. H. P. Zhao, G. Y. Liu, X.-H. Li, G. S. Huang, J. D. Poplawsky, S. T. Penn, V. Dierolf, and N. Tansu, “Growths of staggered InGaN quantum wells light-emitting diodes emitting at 520–525 nm employing graded growth-temperature profile,” Appl. Phys. Lett. 95(6), 061104 (2009). [CrossRef]

, 30

30. H. P. Zhao, G. Y. Liu, and N. Tansu, “Analysis of InGaN-delta-InN quantum wells for light-emitting diodes,” Appl. Phys. Lett. 97(13), 131114 (2010). [CrossRef]

], and the application of patterned sapphire substrates (PSS) to reduce the threading dislocation density and overcome the nonradiative recombination [31

31. Y.-J. Lee, H.-C. Kuo, T.-C. Lu, S.-C. Wang, K. W. Ng, K. M. Lau, Z.-P. Yang, A. S.-P. Chang, and S.-Y. Lin, “Study of GaN-based light-emitting diodes grown on chemical wet-etching-patterned sapphire substrate with V-shaped pits roughening surfaces,” J. Lightwave Technol. 26(11), 1455–1463 (2008). [CrossRef]

].

4. Conclusions

In summary, we have investigated the carriers transferring and recombining mechanism of the MOCVD-grown InGaN/GaN MQWs over the excitation power range of 0.001 to 50 mW and the temperature range of 6 to 300 K. The S- and W-shaped temperature dependences of the emission energy and linewidth reflect the conversion of the carrier transferring mechanisms from nonthermalized to thermalized distribution of localized carriers, and finally to the regular thermalization of the carriers. The disappearance of the S- and W-shaped temperature dependences with increasing excitation power, is attributed to the reduced localization effect. The initial decreasing in the W-shaped temperature dependent linewidth strengthens first and then weakens with increasing excitation power, which we attribute to the exponentially increased density of states with energy in the band tail. The excitation power dependence of the emission intensity, together with that of the emission energy and linewidth, shows that the emission process of the MQWs is dominated by the radiative recombination at low temperature, and by nonradiative recombination at room temperature within low excitation range. The conclusion is also manifested in the excitation power dependence of the IQE. It is improved due to the pronounced enhancement of the radiative recombination mechanism at room temperature with increasing excitation power, and then tends to a constant with further increasing excitation power, this is because when band-filling effect dominates, the injected carriers escape more easily from localized states, especially at room temperature. Accordingly, we can conclude that to achieve a high-quantum efficiency of InGaN-based LED, it would be essential to overcome the nonradiative recombination, weaken the internal electric field in the QW, and increase the depth of localized states to suppress carriers escaping to extended states. The experimental results will provide a useful guidance to fabricate a high-performance LED with high-quantum efficiency.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grant No. 10874101), by the Science Foundation of Shandong province, China (Grant No. Y2008A10), and by National Basic Research Program of China (973 Program) through Grant No. 2009CB930503.

References and links

1.

S. Nakamura, S. Pearton, and G. Fasol, The Blue Laser Diode (Springer, Berlin, 2000).

2.

S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, H. Kiyoku, and Y. Sugimoto, “InGaN-based multi-quantum-well-structure laser diodes,” Jpn. J. Appl. Phys. 35(Part 2, No. 1B), L74–L76 (1996). [CrossRef]

3.

T. Mukai, H. Narimatsu, and S. Nakamura, “Amber InGaN-based light-emitting diodes operable at high ambient temperatures,” Jpn. J. Appl. Phys. 37(Part 2, No. 5A), L479–L481 (1998). [CrossRef]

4.

S. Chichibu, T. Sota, K. Wada, and S. Nakamura, “Exciton localization in InGaN quantum well devices,” J. Vac. Sci. Technol. B 16(4), 2204–2214 (1998). [CrossRef]

5.

G. Sun, G. B. Xu, Y. J. Ding, H. P. Zhao, G. Y. Liu, J. Zhang, and N. Tansu, “Investigation of fast and slow decays in InGaN/GaN quantum wells,” Appl. Phys. Lett. 99(8), 081104 (2011). [CrossRef]

6.

Y. Yamane, K. Fujiwara, and J. K. Sheu, “Largely variable electroluminescence efficiency with current and temperature in a blue (In, Ga)N multiple-quantum-well diode,” Appl. Phys. Lett. 91(7), 073501 (2007). [CrossRef]

7.

J. Zhang and N. Tansu, “Improvement in spontaneous emission rates for InGaN quantum wells on ternary InGaN substrate for light-emitting diodes,” J. Appl. Phys. 110(11), 113110 (2011). [CrossRef]

8.

D. A. B. Miller, D. S. Chemla, T. C. Damen, A. C. Gossard, W. Wiegmann, T. H. Wood, and C. A. Burrus, “Electric field dependence of optical absorption near the band gap of quantum-well structures,” Phys. Rev. B Condens. Matter 32(2), 1043–1060 (1985). [CrossRef] [PubMed]

9.

Y.-H. Cho, G. H. Gainer, A. J. Fischer, J. J. Song, S. Keller, U. K. Mishra, and S. P. DenBaars, “‘S-shaped’ temperature-dependent emission shift and carrier dynamics in InGaN/GaN multiple quantum wells,” Appl. Phys. Lett. 73(10), 1370–1372 (1998). [CrossRef]

10.

Y.-H. Cho, B. D. Little, G. H. Gainer, J. J. Song, S. Keller, U. K. Mishra, and S. P. DenBaars, “Carrier dynamics of abnormal temperature-dependent emission shift in MOCVD-grown InGaN epilayers and InGaN/GaN quantum wells,” MRS Internet J. Nitride Semicond. Res. 4S1, G2.4 (1999).

11.

H. P. D. Schenk, M. Leroux, and P. de Mierry, “Luminescence and absorption in InGaN epitaxial layers and the van Roosbroeck–Shockley relation,” J. Appl. Phys. 88(3), 1525–1534 (2000). [CrossRef]

12.

K. S. Ramaiah, Y. K. Su, S. J. Chang, B. Kerr, H. P. Liu, and I. G. Chen, “Characterization of InGaN/GaN multi-quantum-well blue-light-emitting diodes grown by metal organic chemical vapor deposition,” Appl. Phys. Lett. 84(17), 3307–3309 (2004). [CrossRef]

13.

G. Franssen, T. Suski, M. Kryśko, A. Khachapuridze, R. Kudrawiec, J. Misiewicz, A. Kamińska, E. Feltin, and N. Grandjean, “Built-in electric field and large Stokes shift in near-lattice-matched GaN/AlInN quantum wells,” Appl. Phys. Lett. 92(20), 201901 (2008). [CrossRef]

14.

K. S. Ramaiah, Y. K. Su, S. J. Chang, C. H. Chen, F. S. Juang, H. P. Liu, and I. G. Chen, “Studies of InGaN/GaN multiquantum-well green-light-emitting diodes grown by metalorganic chemical vapor deposition,” Appl. Phys. Lett. 85(3), 401–403 (2004). [CrossRef]

15.

D. Monroe, “Hopping exponential band tails,” Phys. Rev. Lett. 54(2), 146–149 (1985). [CrossRef] [PubMed]

16.

S. D. Baranovskii, R. Eichmann, and P. Thomas, “Temperature-dependent exciton luminescence in quantum wells by computer simulation,” Phys. Rev. B 58(19), 13081–13087 (1998). [CrossRef]

17.

M. Grünewald, B. Movaghar, B. Pohlmann, and D. Würtz, “Hopping theory of band-tail relaxation in disordered semiconductors,” Phys. Rev. B Condens. Matter 32(12), 8191–8196 (1985). [CrossRef] [PubMed]

18.

K. Kazlauskas, G. Tamulaitis, A. Žukauskas, M. A. Khan, J. W. Yang, J. Zhang, G. Simin, M. S. Shur, and R. Gaska, “Double-scaled potential profile in a group-III nitride alloy revealed by Monte Carlo simulation of exciton hopping,” Appl. Phys. Lett. 83(18), 3722–3724 (2003). [CrossRef]

19.

K. Kazlauskas, G. Tamulaitis, P. Pobedinskas, A. Žukauskas, M. Springis, C.-F. Huang, Y.-C. Cheng, and C. C. Yang, “Exciton hopping in InxGa1−xN multiple quantum wells,” Phys. Rev. B 71(8), 085306 (2005). [CrossRef]

20.

P. G. Eliseev, P. Perlin, J. Lee, and M. Osiński, “Blue temperature-induced shift and band-tail emission in InGaN-based light sources,” Appl. Phys. Lett. 71(5), 569–571 (1997). [CrossRef]

21.

P. G. Eliseev, “The red σ2/kT spectral shift in partially disordered semiconductors,” J. Appl. Phys. 93(9), 5404–5415 (2003). [CrossRef]

22.

J. Orenstein and M. Kastner, “Photocurrent transient spectroscopy: measurement of the density of localized states in a-As2Se3,” Phys. Rev. Lett. 46(21), 1421–1424 (1981). [CrossRef]

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I. Mártil, E. Redondo, and A. Ojeda, “Influence of defects on the electrical and optical characteristics of blue light-emitting diodes based on III–V nitrides,” J. Appl. Phys. 81(5), 2442–2444 (1997). [CrossRef]

24.

X. A. Cao, E. B. Stokes, P. M. Sandvik, S. F. LeBoeuf, J. Kretchmer, and D. Walker, “Diffusion and tunneling currents in GaN/InGaN multiple quantum well light-emitting diodes,” IEEE Electron Device Lett. 23(9), 535–537 (2002). [CrossRef]

25.

H. P. Zhao, G. Y. Liu, J. Zhang, J. D. Poplawsky, V. Dierolf, and N. Tansu, “Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells,” Opt. Express 19(S4Suppl 4), A991–A1007 (2011). [CrossRef] [PubMed]

26.

H. P. Zhao and N. Tansu, “Optical gain characteristics of staggered InGaN quantum wells lasers,” J. Appl. Phys. 107(11), 113110 (2010). [CrossRef]

27.

G. Y. Liu, H. P. Zhao, J. Zhang, J. H. Park, L. J. Mawst, and N. Tansu, “Selective area epitaxy of ultra-high density InGaN quantum dots by diblock copolymer lithography,” Nanoscale Res. Lett. 6(1), 342 (2011). [CrossRef] [PubMed]

28.

H. P. Zhao, G. Y. Liu, X.-H. Li, G. S. Huang, J. D. Poplawsky, S. T. Penn, V. Dierolf, and N. Tansu, “Growths of staggered InGaN quantum wells light-emitting diodes emitting at 520–525 nm employing graded growth-temperature profile,” Appl. Phys. Lett. 95(6), 061104 (2009). [CrossRef]

29.

R. M. Farrell, P. S. Hsu, D. A. Haeger, K. Fujito, S. P. DenBaars, J. S. Speck, and S. Nakamura, “Low-threshold-current-density AlGaN-cladding-free m-plane InGaN/GaN laser diodes,” Appl. Phys. Lett. 96(23), 231113 (2010). [CrossRef]

30.

H. P. Zhao, G. Y. Liu, and N. Tansu, “Analysis of InGaN-delta-InN quantum wells for light-emitting diodes,” Appl. Phys. Lett. 97(13), 131114 (2010). [CrossRef]

31.

Y.-J. Lee, H.-C. Kuo, T.-C. Lu, S.-C. Wang, K. W. Ng, K. M. Lau, Z.-P. Yang, A. S.-P. Chang, and S.-Y. Lin, “Study of GaN-based light-emitting diodes grown on chemical wet-etching-patterned sapphire substrate with V-shaped pits roughening surfaces,” J. Lightwave Technol. 26(11), 1455–1463 (2008). [CrossRef]

OCIS Codes
(160.4760) Materials : Optical properties
(160.6000) Materials : Semiconductor materials

ToC Category:
Materials

History
Original Manuscript: December 12, 2011
Revised Manuscript: January 11, 2012
Manuscript Accepted: January 27, 2012
Published: February 1, 2012

Citation
Huining Wang, Ziwu Ji, Shuang Qu, Gang Wang, Yongzhi Jiang, Baoli Liu, Xiangang Xu, and Hirofumi Mino, "Influence of excitation power and temperature on photoluminescence in InGaN/GaN multiple quantum wells," Opt. Express 20, 3932-3940 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-4-3932


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References

  1. S. Nakamura, S. Pearton, and G. Fasol, The Blue Laser Diode (Springer, Berlin, 2000).
  2. S. Nakamura, M. Senoh, S. Nagahama, N. Iwasa, T. Yamada, T. Matsushita, H. Kiyoku, and Y. Sugimoto, “InGaN-based multi-quantum-well-structure laser diodes,” Jpn. J. Appl. Phys.35(Part 2, No. 1B), L74–L76 (1996). [CrossRef]
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