OSA's Digital Library

Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 18 — Aug. 27, 2012
  • pp: 20576–20581

Optics InfoBase > Optics Express > Volume 20 > Issue 18 > Page 20576

« Show journal navigation

Broadband and wide-angle distributed Bragg reflectors based on amorphous germanium films by glancing angle deposition

Jung Woo Leem and Jae Su Yu  »View Author Affiliations


Optics Express, Vol. 20, Issue 18, pp. 20576-20581 (2012)
http://dx.doi.org/10.1364/OE.20.020576


View Full Text Article

Acrobat PDF (1526 KB)


Advanced Search

Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

We fabricated the distributed Bragg reflectors (DBRs) with amorphous germanium (a-Ge) films consisted of the same materials at a center wavelength (λc) of 1.33 μm by the glancing angle deposition. Their optical reflectance properties were investigated in the infrared wavelength region of 1-1.9 μm at incident light angles (θinc) of 8-70°, together with the theoretical analysis using a rigorous coupled-wave analysis simulation. The two alternating a-Ge films at the incident vapor flux angles of 0 and 75° were formed as the high and low refractive index materials, respectively. The a-Ge DBR with only 5 periods exhibited a normalized stop bandwidth (∆λ/λc) of ~24.1%, maintaining high reflectance (R) values of > 99%. Even at a high θinc of 70°, the ∆λ/λc was ~21.9%, maintaining R values of > 85%. The a-Ge DBR with good uniformity was obtained over the area of a 2 inch Si wafer. The calculated reflectance results showed a similar tendency to the measured data.

© 2012 OSA

1. Introduction

Thin films with inclined micro- or nano-columnar structures which were formed by the glancing angle deposition (GLAD) [1

K. Robbie and M. J. Brett, “Sculptured thin films and glancing angle deposition: Growth mechanics and applications,” J. Vac. Sci. Technol. A 15(3), 1460–1465 (1997). [CrossRef]

–3

S. J. Jang, Y. M. Song, H. J. Choi, J. S. Yu, and Y. T. Lee, “Structural and optical properties of silicon by tilted angle evaporation,” Surf. Coat. Tech. 205, S447–S450 (2010). [CrossRef]

] have attracted much interest in recent years. The GLAD allows the construction of three-dimensional (3D) material structures through the self-shadowing effect during the deposition. The optical properties of inclined columnar thin films strongly depend on the resulting morphological structure which can be controlled by the deposition conditions, especially by the glancing angle of incident vapor flux. The highly tilted angle of incident vapor flux enhances the atomic self-shadowing effect, which leads to the high-porous films with a low refractive index (low-n) [4

Y. Zhong, Y. C. Shin, C. M. Kim, B. G. Lee, E. H. Kim, Y. J. Park, K. M. A. Sobahan, C. K. Hwangbo, Y. P. Lee, and T. G. Kim, “Optical and electrical properties of indium tin oxide thin films with tilted and spiral microstructures prepared by oblique angle deposition,” J. Mater. Res. 23(9), 2500–2505 (2008). [CrossRef]

,5

J. W. Leem and J. S. Yu, “Glancing angle deposited ITO films for efficiency enhancement of a-Si:H/μc-Si:H tandem thin film solar cells,” Opt. Express 19(S3 Suppl 3), A258–A268 (2011). [CrossRef] [PubMed]

]. Therefore, the optical thin-film coatings and components consisting only of a single material might be realized by the GLAD. This advantage makes the GLAD technique very promising for optical and optoelectronic device applications. The fabrication of single material structures by the GLAD has been reported as antireflection coatings with air ambient and reflectors for various devices including light emitting diodes, laser diodes, solar cells, sensors, and optical microresonators [6

S. Chhajed, M. F. Schubert, J. K. Kim, and E. F. Schubert, “Nanostructured multilayer graded-index antireflection coating for Si solar cells with broadband and omnidirectional characteristics,” Appl. Phys. Lett. 93(25), 251108 (2008). [CrossRef]

–9

Y. C. Peng, C. C. Kao, H. W. Huang, J. T. Chu, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Fabrication and characteristics of GaN-based microcavity light-emitting diodes with high reflectivity AlN/GaN distributed Bragg reflectors,” Jpn. J. Appl. Phys. 45(4B), 3446–3448 (2006). [CrossRef]

]. Generally, distributed Bragg reflectors (DBRs) consisting of many layers of alternating high and low refractive index (i.e., alternative high-n/low-n materials), their reflectivity and bandwidth rely on the refractive index contrast of the constituent materials [9

Y. C. Peng, C. C. Kao, H. W. Huang, J. T. Chu, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Fabrication and characteristics of GaN-based microcavity light-emitting diodes with high reflectivity AlN/GaN distributed Bragg reflectors,” Jpn. J. Appl. Phys. 45(4B), 3446–3448 (2006). [CrossRef]

–11

Y. H. Lin, C. L. Wu, Y. H. Pai, and G. R. Lin, “A 533-nm self-luminescent Si-rich SiNx/SiOx distributed Bragg reflector,” Opt. Express 19(7), 6563–6570 (2011). [CrossRef] [PubMed]

]. To achieve high reflectivity over a wide wavelength range, a high refractive index contrast is required. However, the high refractive index contrast is limited by the lack of availability of semiconductor materials with low-n. Additionally, conventional DBRs composed of two different semiconductor materials have fundamental limitations such as low refractive index contrast, material selection, and thermal mismatch [11

Y. H. Lin, C. L. Wu, Y. H. Pai, and G. R. Lin, “A 533-nm self-luminescent Si-rich SiNx/SiOx distributed Bragg reflector,” Opt. Express 19(7), 6563–6570 (2011). [CrossRef] [PubMed]

–13

D. J. Ripin, J. T. Gopinath, H. M. Shen, A. A. Erchak, G. S. Petrich, L. A. Kolodziejski, F. X. Kärtner, and E. P. Ippen, “Oxidized GaAs/AlAs mirror with a quantum-well saturable absorber for ultrashort-pulse Cr4+:YAG laser,” Opt. Commun. 214(1-6), 285–289 (2002). [CrossRef]

]. Therefore, the DBRs consisted of the same material are desirable in practical applications. In the case of germanium (Ge), it has a low absorption and a high refractive index (i.e., nGe> 4) in the long wavelength region. By using the GLAD, the refractive index of Ge can effectively be reduced by inducing nanoscale porosity into the films, which leads to low-n Ge films [14

D. K. Pandya and K. L. Chopra, “Obliquely deposited amorphous Ge films. I. Optical properties,” Phys. Status Solidi, A Appl. Res. 35, 725–734 (1976). [CrossRef]

]. In this work, we reported the optical properties of the amorphous Ge (a-Ge) DBRs, which consisted of alternative high-n/low-n films on silicon (Si) substrates by increasing the number of periods, fabricated by the e-beam evaporation with the GLAD method, together with the theoretical analysis using the rigorous coupled-wave analysis (RCWA) method. For the a-Ge DBR with 5 periods, the wafer-scale uniformity was investigated on a 2 inch Si wafer and the incident angle dependence of the reflectance was also explored.

2. Experimental and simulation modeling details

Figure 1 shows the schematic illustration of process steps for the fabrication of DBRs consisted of alternative high-n/low-n a-Ge film pairs on Si substrates using the GLAD technique via the e-beam evaporation at two different incident vapor flux angles of 0 and 75°. The side-view scanning electron microscope (SEM) images of the fabricated a-Ge DBRs with 1, 3, and 5 periods are also shown in Fig. 1. To fabricate the DBRs consisted of a high-n/low-n a-Ge film pair structure, a-Ge films were deposited on the (100) Si substrates with a size of 20 × 20 mm2 by the e-beam evaporation using the GALD method at room temperature. Prior to the evaporation, the Si substrates were ultrasonically cleaned in acetone, methanol, and de-ionized water for 10 min, respectively, and then dried with a nitrogen gas. The dilute nitric acid rinse was also performed to remove metal contaminants from the surface of the substrates. The Ge granules with 99.99% purity were used as an evaporation source material. The chamber was evacuated to a base pressure of < 1 × 10−6 Torr by using a cryogenic pump. The deposition rate was kept at about 1.5 Å/s using a quartz crystal thickness monitor. For the fabrication of the a-Ge films with a high refractive index contrast, the deposition was carried out at the incident vapor flux angles (θi) of 0 and 75° without substrate rotation. The Ge vapor flux with a high θi of 75° produced the inclined columnar nanostructures in the film due to the enhanced self-shadowing effect, which creates the low-n a-Ge film with a high porosity. The porosity within the film can be estimated by the Bruggemann effective medium approximation [15

J. K. Kim, T. Gessmann, E. F. Schubert, J. Q. Xi, H. Luo, J. Cho, C. Sone, and Y. Park, “GaInN light-emitting diode with conductive omnidirectional reflector having a low-refractive-index indium-tin oxide layer,” Appl. Phys. Lett. 88(1), 013501 (2006). [CrossRef]

]. The porosity of the a-Ge film at θi = 75° was estimated to be ~62.8%. In this calculation, we assumed that the normally deposited a-Ge film at θi = 0° has zero porosity. The quarter-wavelength thicknesses of the a-Ge films at θi = 0 and 75° were calculated to be approximately 77 and 168 nm, respectively, by n = 4.34 at θi = 0° and n = 1.98 at θi = 75° for a center wavelength (λc) of 1.33 μm. As illustrated in Fig. 1, it can be observed that the a-Ge DBRs with different periods were well fabricated on Si substrates. The 1-period DBR is composed of an alternative high-n/low-n a-Ge film structure deposited at θi = 0 and 75°. The thicknesses of a-Ge films deposited at θi = 0 and 75° were approximately 77 ± 3 and 168 ± 5 nm, respectively.

Fig. 1 Schematic illustration of process steps for the fabrication of DBRs consisted of alternative high-n/low-n a-Ge film pairs on Si substrates using the GLAD technique via the e-beam evaporation at two different incident vapor flux angles of 0 and 75° and side-view SEM images of the fabricated a-Ge DBRs with 1, 3, and 5 periods.

The deposited profiles of the fabricated a-Ge DBRs on Si substrates were observed by using a field-emission SEM (LEO SUPRA 55, Carl Zeiss). The optical reflectance was measured by a UV-vis-NIR spectrophotometer (Cary 500, Varian) using a linearly polarized light at near normal incidence of ~8° and the incident angle (θinc) was changed from 20 to 70°. To analyze the refractive index (n) and extinction coefficient (k) of a-Ge films, a spectroscopic ellipsometry (V-VASE, J. A. Woollam Co. Inc.) was used. The relative reflectance mapping was characterized by using a rapid photoluminescence and reflectance mapping system (RPM 2000, Accent). For the theoretical optical analysis of the fabricated a-Ge DBRs, the RCWA calculations were performed using a commercial software (DiffractMOD 3.1, Rsoft Design Group) [16

M. G. Moharam and T. K. Gaylord, “Rigorous coupled-wave analysis of planar-grating diffraction,” J. Opt. Soc. Am. 71(7), 811–818 (1981). [CrossRef]

]. It was assumed that the linearly polarized light enters from air into the DBR structure at incident angles of θinc = 0-70°. The refractive index and extinction coefficient values of Si used in this calculation were referred [17

SOPRA, http://www.sopra-sa.com, Accessed 1 June (2012).

].

3. Results and discussion

Figure 2 shows the (a) measured and (b) calculated reflectance spectra of the a-Ge DBRs with 1-5 periods at a center wavelength of 1.33 μm. The inset of Fig. 2(a) shows the measured refractive index and extinction coefficient of the a-Ge films deposited by GLAD at θi = 0 and 75°. The refractive index values of the a-Ge films at θi = 0 and 75° are 4.34 and 1.98, respectively, at a wavelength of 1.33 μm, exhibiting a high refractive index contrast (i.e., difference, ∆n, of 2.36). The high refractive index contrast enlarges the stop bandwidth with high reflectance values [10

O. Blum, I. J. Fritz, L. R. Dawson, A. J. Howard, T. J. Headley, J. F. Klem, and T. J. Drummond, “Highly reflective, long wavelength AlAsSb/GaAsSb distributed Bragg reflector grown by molecular beam epitaxy on InP substrates,” Appl. Phys. Lett. 66(3), 329–331 (1995). [CrossRef]

]. Generally, the extinction coefficient of the film is related to its optical absorption, depending on the film thickness. The absorption coefficient of the film is an important parameter because the multiple reflections of light could be absorbed within the layer. For DBRs consisting of high-absorption materials, the decrease in reflectance would typically be more dominant with increasing the number of periods of DBRs due to the increased optical absorption in the layers. For a-Ge DBRs, however, as the number of periods was increased, the reflectance was also increased. At above 3 periods, furthermore, the reflectance of a-Ge DBRs was almost saturated at wavelengths of ~1.33 μm. This is caused by the high refractive index contrast between a-Ge films at θi = 0 and 75° as well as their low absorption, as can be seen in the inset of Fig. 2(a). Thus, for the a-Ge film at θi = 0°, the slight increase in the extinction coefficient at wavelengths below than about 1.35 μm did not distinctly affect the reflectance characteristics of the a-Ge DBRs, which confirms that their absorption is small. For the a-Ge DBR with 5 periods, the normalized stop bandwidth (∆λ/λc) was ~24.1% at λc = 1.33 μm, maintaining high reflectance (R) values of > 99%, which is sufficient to ensure broadband high reflectivity for practical device applications. The high reflectance values of R> 99% were observed over a wide wavelength region of 1.23-1.55 μm.

Fig. 2 (a) Measured and (b) calculated reflectance spectra of the a-Ge DBRs with 1-5 periods at a center wavelength of 1.33 μm. The inset of (a) shows the measured refractive index and extinction coefficient of the a-Ge films deposited by GLAD at θi = 0 and 75°. The 2D simulation model of the a-Ge DBR with 5 periods is illustrated in the inset of (b).

The 2D simulation model of the a-Ge DBR with 5 periods is illustrated in the inset of Fig. 2(b). There exist slight differences between the measured and calculated results at some wavelengths. This may be attributed to the simplicity of the geometric simulation model for the fabricated DBR structure, the thickness error of deposited films, and the refractive index mismatch of Si used in these experiments and calculations. Nevertheless, the overall trend appears to be similar for the measured and calculated results, as shown in Fig. 2.

Figure 3 shows the measured relative reflectance mapping images of (a) the ‘KHU’-patterned a-Ge DBR on the Si substrate and (b) the a-Ge DBR on a 2 inch Si wafer for 5 periods at a wavelength of 1.33 μm. The ‘KHU’-patterned 5-period a-Ge DBR was fabricated on the Si substrate with a half size of 2 inch wafer using a simple and cheap transparent plastic adhesive tape as the shadow mask. As shown in Fig. 3(a), the reflectance on the patterned surface of the sample (red part) is considerably higher than that on the Si substrate (blue part). Moreover, although there is a slightly different color distribution in the relative reflectance mapping image of the a-Ge DBR with 5 periods on the 2 inch Si wafer due to the GLAD process with no substrate rotation, it exhibits comparatively a uniform relative reflectance over the whole surface of 2 inch Si wafer at a wavelength of 1.33 μm, as can be seen in Fig. 3(b). From these results, the highly tolerant and reflective DBRs with any features can be achieved over a large size by the GLAD process using various pattering techniques.

Fig. 3 Measured relative reflectance mapping images of (a) the ‘KHU’-patterned a-Ge DBR on the Si substrate and (b) the a-Ge DBR on a 2 inch Si wafer for 5 periods at a wavelength of 1.33 μm.

Figure 4(a) shows the measured reflectance spectra of the 5-period a-Ge DBR at incident angles of θinc = 8-70° for linearly polarized light. As the angle of incident light was increased, the high reflectance region was slightly shifted toward the shorter wavelength range and the maximum reflectance value was generally decreased [7

K. Kaminska and K. Robbie, “Birefringent omnidirectional reflector,” Appl. Opt. 43(7), 1570–1576 (2004). [CrossRef] [PubMed]

]. This may be attributed to the variation of the layer thickness [11

Y. H. Lin, C. L. Wu, Y. H. Pai, and G. R. Lin, “A 533-nm self-luminescent Si-rich SiNx/SiOx distributed Bragg reflector,” Opt. Express 19(7), 6563–6570 (2011). [CrossRef] [PubMed]

]. The reflectance value at a wavelength of 1.33 μm was reduced from 99.4% at θinc = 8° to 87.8% at θinc = 70°. The high-reflectivity stop bandwidth at each incident angle also became narrower with increasing the θinc. Nevertheless, the normalized stop bandwidth of the a-Ge DBR with 5 periods was kept up to ∆λ/λc ~21.9% at λc = 1.33 μm, maintaining R values of > 85%, at the high incident light angle of θinc = 70°. For the theoretical analysis of the incident angle-dependent reflectance of the a-Ge DBR, the RCWA calculations were also performed at incident light angles of 0-70°. Figure 4(b) shows the contour plot of the variation of calculated reflectance spectra of the 5-period a-Ge DBR as a function of the incident angle of linearly polarized light. Similarly, the calculated results roughly provide a similar tendency to the measured data in wide ranges of wavelengths and incident angles.

Fig. 4 (a) Measured reflectance spectra of the 5-period a-Ge DBR at incident angles of θinc = 8-70° for linearly polarized light and (b) contour plot of the variation of calculated reflectance spectra of the 5-period a-Ge DBR as a function of the incident angle of linearly polarized light.

4. Conclusion

The high-quality a-Ge DBRs consisted of the same materials were fabricated by the e-beam evaporation with a GLAD method at a center wavelength of λc = 1.33 μm. The a-Ge films with a high refractive index contrast can be obtained by the GLAD process at two different incident vapor flux angles of 0 and 75° for high-n and low-n, respectively. The maximum reflectance of the fabricated a-Ge DBRs was increased with increasing the number of periods. In the case of a-Ge DBRs, the use of only 3 periods provided a sufficient reflectivity for practical device reflectors. For the 5-period a-Ge DBR, the normalized stop bandwidth of ∆λ/λc ~24.1% at λc = 1.33 μm (R> 99%) was obtained. Also, it exhibited the ∆λ/λc of ~21.9%, maintaining R values of > 85% at a high incident light angle of θinc = 70°. The high-reflective a-Ge DBR with 5 periods was uniformly well-formed on the 2 inch Si wafer as well as the ‘KHU’-patterned Si substrate. The theoretically calculated reflectance results by the RCWA simulation exhibited very similar trends to the experimentally measured data. These results can provide a better insight into the broadband and omnidirectional high-reflective DBRs with only few periods made of the same a-Ge materials for various optical and optoelectronic applications.

Acknowledgments

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (No. 2011-0026393) and by the International Collaborative R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government Ministry of Knowledge Economy (No. 20118520010030-11-2-100).

References and links

1.

K. Robbie and M. J. Brett, “Sculptured thin films and glancing angle deposition: Growth mechanics and applications,” J. Vac. Sci. Technol. A 15(3), 1460–1465 (1997). [CrossRef]

2.

F. Liu, M. T. Umlor, L. Shen, J. Weston, W. Eads, J. A. Barnard, and G. J. Mankey, “The growth of nanoscale structured iron films by glancing angle deposition,” J. Appl. Phys. 85(8), 5486–5488 (1999). [CrossRef]

3.

S. J. Jang, Y. M. Song, H. J. Choi, J. S. Yu, and Y. T. Lee, “Structural and optical properties of silicon by tilted angle evaporation,” Surf. Coat. Tech. 205, S447–S450 (2010). [CrossRef]

4.

Y. Zhong, Y. C. Shin, C. M. Kim, B. G. Lee, E. H. Kim, Y. J. Park, K. M. A. Sobahan, C. K. Hwangbo, Y. P. Lee, and T. G. Kim, “Optical and electrical properties of indium tin oxide thin films with tilted and spiral microstructures prepared by oblique angle deposition,” J. Mater. Res. 23(9), 2500–2505 (2008). [CrossRef]

5.

J. W. Leem and J. S. Yu, “Glancing angle deposited ITO films for efficiency enhancement of a-Si:H/μc-Si:H tandem thin film solar cells,” Opt. Express 19(S3 Suppl 3), A258–A268 (2011). [CrossRef] [PubMed]

6.

S. Chhajed, M. F. Schubert, J. K. Kim, and E. F. Schubert, “Nanostructured multilayer graded-index antireflection coating for Si solar cells with broadband and omnidirectional characteristics,” Appl. Phys. Lett. 93(25), 251108 (2008). [CrossRef]

7.

K. Kaminska and K. Robbie, “Birefringent omnidirectional reflector,” Appl. Opt. 43(7), 1570–1576 (2004). [CrossRef] [PubMed]

8.

S. J. Jang, Y. M. Song, C. I. Yeo, C. Y. Park, and Y. T. Lee, “Highly tolerant a-Si distributed Bragg reflector fabricated by oblique angle deposition,” Opt. Mater. Express 1(3), 451–457 (2011). [CrossRef]

9.

Y. C. Peng, C. C. Kao, H. W. Huang, J. T. Chu, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Fabrication and characteristics of GaN-based microcavity light-emitting diodes with high reflectivity AlN/GaN distributed Bragg reflectors,” Jpn. J. Appl. Phys. 45(4B), 3446–3448 (2006). [CrossRef]

10.

O. Blum, I. J. Fritz, L. R. Dawson, A. J. Howard, T. J. Headley, J. F. Klem, and T. J. Drummond, “Highly reflective, long wavelength AlAsSb/GaAsSb distributed Bragg reflector grown by molecular beam epitaxy on InP substrates,” Appl. Phys. Lett. 66(3), 329–331 (1995). [CrossRef]

11.

Y. H. Lin, C. L. Wu, Y. H. Pai, and G. R. Lin, “A 533-nm self-luminescent Si-rich SiNx/SiOx distributed Bragg reflector,” Opt. Express 19(7), 6563–6570 (2011). [CrossRef] [PubMed]

12.

J. Boucart, C. Starck, F. Gaborit, A. Plais, N. Bouché, E. Derouin, J. C. Remy, J. Bonnet-Gamard, L. Goldstein, C. Fortin, D. Carpentier, P. Salet, F. Brillouet, and J. Jacquet, “Metamorphic DBR and tunnel-junction injection: A CW RT monolithic long-wavelength VCSEL,” IEEE J. Sel. Top. Quantum Electron. 5(3), 520–529 (1999). [CrossRef]

13.

D. J. Ripin, J. T. Gopinath, H. M. Shen, A. A. Erchak, G. S. Petrich, L. A. Kolodziejski, F. X. Kärtner, and E. P. Ippen, “Oxidized GaAs/AlAs mirror with a quantum-well saturable absorber for ultrashort-pulse Cr4+:YAG laser,” Opt. Commun. 214(1-6), 285–289 (2002). [CrossRef]

14.

D. K. Pandya and K. L. Chopra, “Obliquely deposited amorphous Ge films. I. Optical properties,” Phys. Status Solidi, A Appl. Res. 35, 725–734 (1976). [CrossRef]

15.

J. K. Kim, T. Gessmann, E. F. Schubert, J. Q. Xi, H. Luo, J. Cho, C. Sone, and Y. Park, “GaInN light-emitting diode with conductive omnidirectional reflector having a low-refractive-index indium-tin oxide layer,” Appl. Phys. Lett. 88(1), 013501 (2006). [CrossRef]

16.

M. G. Moharam and T. K. Gaylord, “Rigorous coupled-wave analysis of planar-grating diffraction,” J. Opt. Soc. Am. 71(7), 811–818 (1981). [CrossRef]

17.

SOPRA, http://www.sopra-sa.com, Accessed 1 June (2012).

OCIS Codes
(230.1480) Optical devices : Bragg reflectors
(310.1860) Thin films : Deposition and fabrication
(310.4165) Thin films : Multilayer design

ToC Category:
Thin Films

History
Original Manuscript: July 17, 2012
Revised Manuscript: August 15, 2012
Manuscript Accepted: August 15, 2012
Published: August 22, 2012

Citation
Jung Woo Leem and Jae Su Yu, "Broadband and wide-angle distributed Bragg reflectors based on amorphous germanium films by glancing angle deposition," Opt. Express 20, 20576-20581 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-18-20576


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. K. Robbie and M. J. Brett, “Sculptured thin films and glancing angle deposition: Growth mechanics and applications,” J. Vac. Sci. Technol. A15(3), 1460–1465 (1997). [CrossRef]
  2. F. Liu, M. T. Umlor, L. Shen, J. Weston, W. Eads, J. A. Barnard, and G. J. Mankey, “The growth of nanoscale structured iron films by glancing angle deposition,” J. Appl. Phys.85(8), 5486–5488 (1999). [CrossRef]
  3. S. J. Jang, Y. M. Song, H. J. Choi, J. S. Yu, and Y. T. Lee, “Structural and optical properties of silicon by tilted angle evaporation,” Surf. Coat. Tech.205, S447–S450 (2010). [CrossRef]
  4. Y. Zhong, Y. C. Shin, C. M. Kim, B. G. Lee, E. H. Kim, Y. J. Park, K. M. A. Sobahan, C. K. Hwangbo, Y. P. Lee, and T. G. Kim, “Optical and electrical properties of indium tin oxide thin films with tilted and spiral microstructures prepared by oblique angle deposition,” J. Mater. Res.23(9), 2500–2505 (2008). [CrossRef]
  5. J. W. Leem and J. S. Yu, “Glancing angle deposited ITO films for efficiency enhancement of a-Si:H/μc-Si:H tandem thin film solar cells,” Opt. Express19(S3Suppl 3), A258–A268 (2011). [CrossRef] [PubMed]
  6. S. Chhajed, M. F. Schubert, J. K. Kim, and E. F. Schubert, “Nanostructured multilayer graded-index antireflection coating for Si solar cells with broadband and omnidirectional characteristics,” Appl. Phys. Lett.93(25), 251108 (2008). [CrossRef]
  7. K. Kaminska and K. Robbie, “Birefringent omnidirectional reflector,” Appl. Opt.43(7), 1570–1576 (2004). [CrossRef] [PubMed]
  8. S. J. Jang, Y. M. Song, C. I. Yeo, C. Y. Park, and Y. T. Lee, “Highly tolerant a-Si distributed Bragg reflector fabricated by oblique angle deposition,” Opt. Mater. Express1(3), 451–457 (2011). [CrossRef]
  9. Y. C. Peng, C. C. Kao, H. W. Huang, J. T. Chu, T. C. Lu, H. C. Kuo, S. C. Wang, and C. C. Yu, “Fabrication and characteristics of GaN-based microcavity light-emitting diodes with high reflectivity AlN/GaN distributed Bragg reflectors,” Jpn. J. Appl. Phys.45(4B), 3446–3448 (2006). [CrossRef]
  10. O. Blum, I. J. Fritz, L. R. Dawson, A. J. Howard, T. J. Headley, J. F. Klem, and T. J. Drummond, “Highly reflective, long wavelength AlAsSb/GaAsSb distributed Bragg reflector grown by molecular beam epitaxy on InP substrates,” Appl. Phys. Lett.66(3), 329–331 (1995). [CrossRef]
  11. Y. H. Lin, C. L. Wu, Y. H. Pai, and G. R. Lin, “A 533-nm self-luminescent Si-rich SiNx/SiOx distributed Bragg reflector,” Opt. Express19(7), 6563–6570 (2011). [CrossRef] [PubMed]
  12. J. Boucart, C. Starck, F. Gaborit, A. Plais, N. Bouché, E. Derouin, J. C. Remy, J. Bonnet-Gamard, L. Goldstein, C. Fortin, D. Carpentier, P. Salet, F. Brillouet, and J. Jacquet, “Metamorphic DBR and tunnel-junction injection: A CW RT monolithic long-wavelength VCSEL,” IEEE J. Sel. Top. Quantum Electron.5(3), 520–529 (1999). [CrossRef]
  13. D. J. Ripin, J. T. Gopinath, H. M. Shen, A. A. Erchak, G. S. Petrich, L. A. Kolodziejski, F. X. Kärtner, and E. P. Ippen, “Oxidized GaAs/AlAs mirror with a quantum-well saturable absorber for ultrashort-pulse Cr4+:YAG laser,” Opt. Commun.214(1-6), 285–289 (2002). [CrossRef]
  14. D. K. Pandya and K. L. Chopra, “Obliquely deposited amorphous Ge films. I. Optical properties,” Phys. Status Solidi, A Appl. Res.35, 725–734 (1976). [CrossRef]
  15. J. K. Kim, T. Gessmann, E. F. Schubert, J. Q. Xi, H. Luo, J. Cho, C. Sone, and Y. Park, “GaInN light-emitting diode with conductive omnidirectional reflector having a low-refractive-index indium-tin oxide layer,” Appl. Phys. Lett.88(1), 013501 (2006). [CrossRef]
  16. M. G. Moharam and T. K. Gaylord, “Rigorous coupled-wave analysis of planar-grating diffraction,” J. Opt. Soc. Am.71(7), 811–818 (1981). [CrossRef]
  17. SOPRA, http://www.sopra-sa.com , Accessed 1 June (2012).

Cited By

 Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1 Fig. 2 Fig. 3
 
Fig. 4
 

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited