Unil Perera


A. G. Unil Perera is a Sri Lankan-born American physicist with an assortment of research interests in experimental condensed matter physics, especially semiconductor infrared detectors and applications. He has authored over 200 publications covering a variety of disciplines inside. He is a Regents’ Professor of Physics at Georgia State University, in Atlanta, Georgia. After his basic Education in Sri Lanka, he obtained his doctoral degree in physics from the University of Pittsburgh under the supervision of Darry D. Coon. During his graduate research, he developed a detector, which can detect infrared radiation without the use of any amplifiers.. Then he introduced the concept of a two-terminal artificial neuron, a parallel asynchronous processing based on artificial neurons, Neural Networks 2, 143,.( Phys. Rev. Lett., 58, 1139,.

Early life and education

Unil Perera was born in Sri Lanka to Mr. A. G. Weyman Perera and Mrs. Daya Perera. He had his pre-college education at Ananda College of Colombo, the premier Buddhist School in Sri Lanka founded by the Theosophical Society headed by the US visionary Henry Steel Olcott. He obtained a BSc in physics in 1981 from the University of Colombo, Sri Lanka. After serving as an assistant lecturer for one year, he came to University of Pittsburgh and obtained a PhD degree in experimental solid state physics in 1987. After a brief postdoctoral position at the University of Pittsburgh, he was appointed as a research assistant professor in January 1988. In 1992, he accepted an assistant professor position at Georgia State University. He has held visiting research positions at the Institute for Microstructural Studies, National Research Council, Ottawa, Canada, National Institute of Fundamental Studies, Sri Lanka, and, Singapore.

Recognition

Perera was elected a Fellow of the American Physical Society in 2005 and as a of the Institute Electrical and Electronics Engineers (IEEE) in 2012, he was recognized as the award in 2020.
He became a full professor at GSU in 2001. In 2009, College of Arts and Sciences at GSU awarded him “Outstanding Faculty Scholarship Award”, followed by the “Alumni Distinguished Professor” Award from GSU and the “Carl R Nave Award for the Outstanding Educator in Physics” from the Society of Physics Students, both in 2010. In 2013 GSU awarded him the title Regents’ Professor of Physics.
In 2012, Sri Lanka Foundation, a non-profit organization with a mission to educate the citizens of the world on Sri Lanka and the achievements of its people gave Perera their highest award” Life Time Achievement Award”. He was instrumental in establishing joint tri partite research programs with the Institute of Fundamental Science, Hantana, Sri Lanka and the IIT- Chennai and GSU. He also established a joint PhD program with IFS, where IFS junior researchers can obtain a PhD at GSU.
He also organized and chaired an international conference on Infrared detectors in Sri Lanka. He as a member of the APS international Affairs committee, organized webinars on “Graduate Studies in US” for the south East Asian audiences.

Research

  • Homojunction Interfacial work function internal photoemission IR Detectors : Rather than using specific semiconductors for specific wavelength range detection, he developed detectors which can detect IR radiation over a wide range irrespective of the semiconductor material. The idea is based on Metal insulator transitions, where a semiconductor material will behave as a metal under high doping. This will develop an interfacial workfunction at an interface between a highly doped and intrinsic semiconductor junction. The energy gap can be controlled by the doping, leading to a wavelength tailorable detector. 3168-3170, JAP 77 915-924, APL 66, 2262–2264 He used commercially available p-i-n diodes, to demonstrate a far infrared detector concept which can be used with any semiconductor material system. A complete model to explain the wavelength tunable homojunction interfacial workfunction internal photoemission detector concepts was developed. This idea was successfully tested in MBE grown GaAs and SI HIWIP FIR detectors. JAP 81 3316–3319, 1997, APL 72 2307-2309.
  • Quantum Well IR Detectors : Perera demonstrated that the Quantum well detectors can be developed to detect LWIR and VLWIR detectors by continuously extending the threshold to A 14.5 micron threshold quantum well infrared detector demonstrated in 1990. He designed and successfully demonstrated a 28-micron threshold QWIP in 1998 and extended the threshold wavelength to 32 micron in 2000. The November 2000 issue of PHOTONICS SPECTRA, TECHNOLOGY WORLD BRIEFS featured this work. In each case it was the longest threshold detected in QWIPS at the time. We reported Non-monotonic dependence of the polarization extinction ratio on the parameters of the diffraction grid in QWIP detectors in 2010.. Two back-to-back connected p-i-n photodiodes with InGaAs/GaAs and GaAs/AlGaAs-based quantum wells integrated within the n-regions was designed to detect five bands covering visible to long-wave infrared was demonstrated using a GaAs-based n-p-n-architecture.
  • Heterojunction Interfacial Work function Internal Photoemission IR detectors The hole –hole transitions limited the HIWIP detector tailorability and also the high doping contributed to the dark current. This led to his development of Heterojunction detectors combining the free carrier idea from HIWIP and the adjustable barrier ideas from MBE growth and Quantum Well infrared detectors. .
  • Quantum Dot and Ring IR detectors : Multicolor QDIP detectors were demonstrated. The effect of well width on the dot in a well structure was studied. The three color QDIP results were reported in the December 2003 issue of LASER FOCUS WORLD, NEWSBREAKS. Room temperature operation of a QDIP was demonstrated. . These ideas were extended to detect multiband detection in to the terahertz range., APL 92, 011117, ). Quantum rings obtained by annealing the dot structures were demonstrated to detect terahertz radiation. To understand the performance the effect of the dot size and distribution on the intersublevel transmission and absorption coefficients of III-V systems was calculated.
  • Multiband Junction Detectors: A dual band homojunction detector was demonstrated. [Appl. Phys. Lett, 86, 143510, & APL 89, 061112, The idea was extended to UV – IR dual band heterojunction detectors,