Unil Perera

Key takeaways

Unil Perera belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Unil Perera to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Unil Perera from memory before moving on to harder problems.

Reference excerpt

A. G. Unil Perera is a Sri Lanka-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. 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 (applied) 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 (IR) radiation without the use of any amplifiers. (Solid State Electronics, 29, 929, (1986). Then he introduced the concept of a two-terminal artificial (semiconductor) neuron (International Journal of Electronics, 63, 61, (1987), a parallel asynchronous processing based on artificial neurons (Int journal of Infrared and Millimeter Waves, 9, 1037, 1987), Neural Networks 2, 143, (1989).( Phys. Rev. Lett., 58, 1139, (1987, Neural Information Processing Systems", 201–210, Edited by Dana Z. Anderson, A. I. P., New York, (1988)).

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 (First Class Honors) 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 Technical University, Singapore.

Recognition Perera was elected a Fellow of the American Physical Society (APS) in 2005 and as a Fellow of the Society of Photo Instrumentation Engineers (SPIE) of the Institute Electrical and Electronics Engineers (IEEE) in 2012. He was recognized as the IEEE Photonics Society distinguished lecturer 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 ”Lifetime Achievement Award”. He was instrumental in establishing joint tri partite research programs with the National Institute of Fundamental Science, Sri Lanka (NIFS) and IIT Chennai and GSU. He also established a joint PhD program with NIFS, where NIFS 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 Southeast Asian audiences.

Research

Homojunction Interfacial work function internal photoemission IR Detectors (HIWIP): 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 (energy gap) 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. (APL, 60 (25) 3168-3170 (1992), JAP 77 (2) 915-924 (1995), APL 66, 2262–2264 (1995) He used commercially available PIN diodes, (Silicon, Ge and InGaAs) to demonstrate a far infrared concept which can be used with any semiconductor material system. [App. Phys. Lett., 55, 1738, (1989), Appl. Phys. Lett., 60, 3168, (1992), Superlattice and Microstructures 14, 123–128 (1993). LASER FOCUS WORLD, NEWSBREAKS, featured this work in their August 1992 issue. Based on these ideas a wavelength tunable infrared detector patent was awarded. [U.S. Patent # 5,030,831, issued on July 9, 1991.] A complete model to explain the wavelength tunable homojunction interfacial workfunction internal photoemission (HIWIP) detector concepts was developed. [J. Appl. Phys, 77, 915–924, (1995), Appl. Phys. Lett. 66, 2262–2264, (1995)] This idea was successfully tested in MBE grown GaAs and SI HIWIP FIR detectors. JAP 81(7) 3316–3319, 1997, APL 72(18) 2307-2309 (1998). Quantum well infrared photodetector (QWIP): Perera demonstrated that the quantum well detectors can be developed to detect LWIR (long-wavelength infrared) and VLWIR detectors by continuously extending the threshold to: (a) A 14.5 micron threshold quantum well infrared detector demonstrated in 1990.[ Appl. Phys. Lett., 60, 3022, (1992).] (b) Designed and successfully demonstrated a 28-micron threshold QWIP in 1998 [Appl. Phys. Lett. 72, 1596–1598, (1998)] (c) Extended the threshold wavelength to 32 micron in 2000. [Appl. Phys. Lett, 77 741–743, (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. He reported non-monotonic dependence of the polarization extinction ratio on the parameters of the diffraction grid in QWIP detectors in 2010. (IEEE J of Quantum Electronics 46, 6, 877, (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. {APL, 97, 231102 (2010) }

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Worked examples

Example 1 — a first encounter with Unil Perera

Start with the simplest possible case. Write down what Unil Perera claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Unil Perera before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Unil Perera ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Unil Perera

In research: Unil Perera appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Unil Perera in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Unil Perera is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alumni of the University of Colombo, American physicists, Georgia State University faculty, so understanding it makes those chapters shorter.
In everyday life: Look for Unil Perera outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Unil Perera in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Unil Perera means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Unil Perera out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Unil Perera in simple terms?

A. G.

Why does Unil Perera matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Unil Perera?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Unil Perera.