TY - JOUR
T1 - Light coupling characteristics of corrugated quantum-well infrared photodetectors
AU - Choi, Kwong Kit
AU - Leung, Kok Ming
AU - Tamir, Theodor
AU - Monroy, Carlos
N1 - Funding Information:
Manuscript received April 12, 2003; revised November 3, 2003. This work was supported in part by the U.S. Army Research Office under Grant DAAD19-99-1-0126. K.-K. Choi and C. Monroy are with the Electro-Optics and Photonic Division, U.S. Army Research Laboratory, Adelphi, MD 20783-1145 USA (e-mail: [email protected]). K.-M. Leung is with the Department of Computer and Information Sciences, Polytechnic University, Brooklyn, NY 11201 USA. T. Tamir is with the Electrical and Computer Engineering Department, Polytechnic University, Brooklyn, NY 11201 USA. Digital Object Identifier 10.1109/JQE.2003.821531
PY - 2004/2
Y1 - 2004/2
N2 - Corrugated quantum-well infrared photodetectors (C-QWIPs) offer simple detector architectures for large-format infrared focal plane arrays (FPAs). The detector relies on inclined sidewalls to couple normal incident light into the absorbing material. Based on a simplified geometrical-optics (GO) model, this light coupling scheme is expected to be effective with little wavelength dependence. In this work, we apply the modal transmission-line (MTL) modeling technique to study in detail its light coupling characteristics and compare the results with the GO model and experimental data. We find that the results of the GO model agree reasonably well with those of the rigorous MTL model for corrugations with metal cover, and both modeling procedures are consistent with experimental data. In particular, both models predict similar increase in the quantum efficiency η with the size of the corrugations, and both indicate similar limiting η when the corrugation becomes very large. For linear corrugations with thick substrates, the maximum η is about 30%. On the other hand, there are also significant differences between the two models when the effects of phase coherence are important. Since the phase of the radiation is taken into account in the MTL formalism but not in the GO formalism, the MTL model is more generally applicable and is more capable of explaining different detector characteristics. For example, it predicts a smaller η for air or epoxy-covered C-QWIPs because of finite optical transmission through the sharp corners in the corrugations, and it indicates an oscillatory function of η because of the existence of optical fringes. It also reveals the wavelength dependence of the coupling, which becomes more pronounced as the thickness of the substrate layer is reduced.
AB - Corrugated quantum-well infrared photodetectors (C-QWIPs) offer simple detector architectures for large-format infrared focal plane arrays (FPAs). The detector relies on inclined sidewalls to couple normal incident light into the absorbing material. Based on a simplified geometrical-optics (GO) model, this light coupling scheme is expected to be effective with little wavelength dependence. In this work, we apply the modal transmission-line (MTL) modeling technique to study in detail its light coupling characteristics and compare the results with the GO model and experimental data. We find that the results of the GO model agree reasonably well with those of the rigorous MTL model for corrugations with metal cover, and both modeling procedures are consistent with experimental data. In particular, both models predict similar increase in the quantum efficiency η with the size of the corrugations, and both indicate similar limiting η when the corrugation becomes very large. For linear corrugations with thick substrates, the maximum η is about 30%. On the other hand, there are also significant differences between the two models when the effects of phase coherence are important. Since the phase of the radiation is taken into account in the MTL formalism but not in the GO formalism, the MTL model is more generally applicable and is more capable of explaining different detector characteristics. For example, it predicts a smaller η for air or epoxy-covered C-QWIPs because of finite optical transmission through the sharp corners in the corrugations, and it indicates an oscillatory function of η because of the existence of optical fringes. It also reveals the wavelength dependence of the coupling, which becomes more pronounced as the thickness of the substrate layer is reduced.
KW - Diffraction
KW - Electromagnetic modeling
KW - Focal plane array (FPA)
KW - Infrared detector
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U2 - 10.1109/JQE.2003.821531
DO - 10.1109/JQE.2003.821531
M3 - Article
AN - SCOPUS:1242263850
SN - 0018-9197
VL - 40
SP - 130
EP - 142
JO - IEEE Journal of Quantum Electronics
JF - IEEE Journal of Quantum Electronics
IS - 2
ER -