26 July 1999 Sensitivity enhancement of quantum well infrared photodetectors with a pseudorandom optical coupler by confinement of internal multireflection
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Abstract
We investigated the sensitivity enhancement of quantum well IR photodetectors (QWIP) with the pseudo-random optical coupler. We fabricated QWIP focal plane arrays (FPA) containing AlGaAs/GaAs multi-quantum wells (MQW) detecting 7-8 micrometers IR regions. After QWIP-FPA and read-out integrated circuits were hybridized, GaAs substrates attached to the back of the FPA were removed. We compared the sensitivity of a QWIP-FPA without a GaAs substrate with that of a QWIP-FPA with the substrate. When the input IR beams illuminated only some pixels in the QWIP-FPA, the output signal from the FPA without GaAs substrate was about ten times higher than that from the FPA with a substrate. The output signals were almost same for both QWIP-FPAs where all pixels were uniformly illuminated by the IR inputs. These result indicate that the reflected beams from the GaAs back surface illuminate another pixels far away from the pixels which input beams strike first, when the FPA has a sufficiently thick GaAs substrate. We confirmed that the pseudo-random grating coupler for QWIP enhanced IR absorption by confining multi internal total reflections in one pixel, when thick substrates were removed.
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Hironori Nishino, Hironori Nishino, Prafulla J. Masalkar, Prafulla J. Masalkar, Yoichiro Sakachi, Yoichiro Sakachi, Yusuke Matsukura, Yusuke Matsukura, Hitoshi Tanaka, Hitoshi Tanaka, Kousaku Yamamoto, Kousaku Yamamoto, Yoshihiro Miyamoto, Yoshihiro Miyamoto, Toshio Fujii, Toshio Fujii, } "Sensitivity enhancement of quantum well infrared photodetectors with a pseudorandom optical coupler by confinement of internal multireflection", Proc. SPIE 3698, Infrared Technology and Applications XXV, (26 July 1999); doi: 10.1117/12.354560; https://doi.org/10.1117/12.354560
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