Bandgap tunability achievable using metamorphic epitaxy enables maximization of photodetector performance
at target wavelengths. However, an increase in threading dislocation density (TDD), which is inherent for the growth of
relaxed, lattice-mismatched layers, could offset this advantage and severely limit detector performance. In this regard,
we are investigating the performance of InxGa1-xAs and InzGa1-zP p-i-n photodetectors as a function of TDD, by utilizing
a number of different InxGa1-xAs buffer designs. In particular, internally lattice-matched metamorphic In0.20Ga0.80As and
In0.68Ga0.32P individual p-i-n detectors are studied to optimize the buffer design and performance of optically-aligned
In0.68Ga0.32P/In0.20Ga0.80As visible/near-infrared dual-photodetectors. Reverse-bias dark current density of In0.68Ga0.32P
detectors were found to be extremely sensitive to TDD compared to that observed for In0.20Ga0.80As detectors. Nearidentical
spectral response curves were obtained for both detectors as a function of TDD due to the relative insensitivity
of the p-i-n detector structure to the minority carrier lifetime. A comprehensive comparison between the different graded
buffer designs, TDD achieved and photodetector characteristics are presented.
We present room-temperature AlGaAsSb/InGaAsSb heterojunction phototransistors (HPT) with a cutoff wavelength (50% of maximum quantum efficiency) of 2.4 μm and 2.15 μm. AlGaAsSb/InGaAsSb HPT structures were grown by molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD). This work is a continuation of a preceding project, which was carried out using liquid phase epitaxy (LPE) grown AlGaAsSb/InGaAsSb/GaSb heterostructures. Although the LPE-related work resulted in the fabrication of an HPT with excellent parameters, MBE and MOCVD - compared to LPE - provides better control over doping levels, composition and width of the AlGaAsSb and InGaAsSb layers, compositional and doping profiles, especially with regard to abrupt heterojunctions. HPT with different diameter of photosensitive area (75, 200, 300 and 1000 μm) were fabricated and characterized. In particular, I-V characteristics, spectral response and noise, as well as detectivity and noise-equivalent-power were determined in a broad range of temperatures and bias voltages. Advantages of HPT integration with diffractive optical elements (DOE) were demonstrated.
Conference Committee Involvement (9)
Metro and Data Center Optical Networks and Short-Reach Links
30 January 2018 | San Francisco, California, United States
Image Sensing Technologies: Materials, Devices, Systems, and Applications IV
12 April 2017 | Anaheim, CA, United States
Optical Metro Networks and Short-Haul Systems IX
31 January 2017 | San Francisco, California, United States
Image Sensing Technologies: Materials, Devices, Systems, and Applications III
20 April 2016 | Baltimore, MD, United States
Optical Metro Networks and Short-Haul Systems VIII
16 February 2016 | San Francisco, California, United States
Image Sensing Technologies: Materials, Devices, Systems, and Applications II
22 April 2015 | Baltimore, MD, United States
Optical Metro Networks and Short-Haul Systems VII
10 February 2015 | San Francisco, California, United States
Image Sensing Technologies: Materials, Devices, Systems, and Applications
7 May 2014 | Baltimore, MD, United States
Optical Metro Networks and Short-Haul Systems VI
4 February 2014 | San Francisco, California, United States
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