Sanjay Krishna is the George R Smith Professor of Engineering in the ECE department at the Ohio State University. He was previously the Director of the Center for High Technology Materials and Professor and Regents Lecturer in the Department of Electrical and Computer Engineering at the University of New Mexico. Sanjay received his M.S. in Electrical Engineering in 1999 and PhD in Applied Physics in 2001 from the University of Michigan. He joined UNM as a tenure track faculty member in 2001. His group is involved with the development of next generation infrared detectors, arrays and imagers. Sanjay received the Gold Medal from IIT, Madras, Ralph Power Junior Faculty Award, IEEE Outstanding Engineering Award, ECE Department Outstanding Researcher Award, School of Engineering Jr Faculty Teaching Excellence Award, NCMR-DIA Chief Scientist Award for Excellence, the NAMBE Young Investigator Award, IEEE-NTC, SPIE Early Career Achievement Award and the ISCS Young Scientist Award. He was also awarded the UNM Teacher of the Year and the UNM Regents Lecturer award. Sanjay has more than 200 peer-reviewed journal articles (h-index=45), two book chapters and ten issued patents. He is the co-founder and CTO of SK Infrared, a start-up involved with the use of IR imaging for dual use applications including early detection of skin cancer. He is a Fellow of IEEE, OSA and SPIE.
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Avalanche photodiodes (APDs) are a promising detector technology for light detection and ranging (LIDAR) systems needed for a variety of DoD and commercial applications. However, a new material that is sensitive to 1.55 μm and has low “excess noise” is needed to achieve the required signal-to-noise. The main issue for improving APD signal-to-noise is to reduce excess noise. Excess noise is inevitable in APDs because impact ionization must occur to obtain a high multiplication gain. One solution to reduce the excess noise is to develop a new material system with favorable impact ionization coefficients. The ratio of electron (α) and hole (β) impact ionization coefficients, defined as k value, is intrinsically defined by the material and is a dominant factor for the APD’s excess noise. In this work, we investigate InAs/AlSb type-II superlattice (T2SL) APD. The superlattices provide us with additional degrees of freedom to engineer the electronic band structure. Our work is building on previous, promising results with the quaternary system AlInAsSb. We have theoretically modeled an InAs/AlSb type II superlattice (T2SL) system that can provide flexibility to engineer the electronic band structure to achieve single carrier impact ionization and reduce the excess noise. The simulation of this T2SL predicts that InAs/AlSb has higher absorption and would work as an electron- APD with low k. We will discuss design, growth, fabrication and IV characterization of this photodiodes.
Recently, a new strategy used to achieve high operation temperature (HOT) infrared photodetectors including cascade devices and alternate materials such as type-II superlattices has been observed. Another method to reduce detector’s dark current is reducing volume of detector material via a concept of photon trapping detector.
In this paper, the performance of a novel HOT detector designing so-called interband cascade type-II MWIR InAs/GaSb superlattice detectors is presented. Detailed analysis of the detector’s performance (such as dark current, RA product, current responsivity, and response time) versus bias voltage and operating temperatures (220 – 400 K) is performed pointing out optimal working conditions. At present stage of technology, the experimentally measured R0A values of interband cascade type-II superlattice detectors at room temperature are higher than those predicted for HgCdTe photodiodes. It is shown that these novel HOT detectors have emerged as competitors of HgCdTe photodetectors.
Dry etching and surface passivation techniques for type-II InAs/GaSb superlattice infrared detectors
Real-time implementation of matched filtering algorithms using adaptive focal-plane array technology
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