ECE Dist. Lecture: III-V Quantum Structures for Infrared Detection

There are many applications that require long wavelength, large, uniform,
reproducible, low cost, stable, and radiation-hard infrared (IR) focal plane arrays (FPAs). For
example, the absorption lines of many gas molecules, such as ozone, water, carbon monoxide,
carbon dioxide, and nitrous oxide occur in the wavelength region from 3 to 15 microns. Thus,
IR imaging systems that operate in the long wavelength IR (LWIR) region (8 – 15 microns)
are required in many space borne applications such as monitoring the global atmospheric
temperature profi les, relative humidity profi les, cloud characteristics, and the distribution of
minor constituents in the atmosphere which are being planned for future NASA Earth and
planetary remote sensing systems.

Currently, we are working on Superlattice detectors, multi-band Quantum Well Infrared
Photodetectors (QWIPs), and Quantum Dot Infrared Photodetector (QDIPs) technologies
suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays.
Due to higher radiation hardness, lower 1/f noise,
and larger array size, the GaAs based QWIP FPAs are
very attractive for such space borne applications.
Furthermore, we have exploited the artifi cial atomlike
properties of epitaxially self-assembled quantum dots
for the development of high operating temperature IR
FPAs. Additionally, the closely lattice-matched material
system of InAs, GaSb, and AlSb, commonly referred
to as the 6.1… material system, has emerged as a
fertile ground for the development of new solid-state
devices. The fl exibility of the system in simultaneously
permitting type-I, type-II staggered, and type-II
broken-gap band alignments has been the basis
for many novel, high-performance heterostructure
devices in recent years, including the GaSb/InAs
type-II superlattice IR detectors. In this presentation
I will discuss the optimization of the detector design,
material growth and processing that has culminated
in realization of III-V based IR detectors, large format
FPAs, and IR cameras which hold great promise for
myriad applications in 3-15 micron wavelength range
in science, medicine, and industry.
Dr. Sarath Gunapala leads the Infrared Photonics
Group at the Jet Propulsion Laboratory. In 2015 he
received NASA's Outstanding Leadership Medal. In
addition to this he is a Fellow of SPIE, IEEE, & OSA. He is
a senior research scientist and a Fellow at the Jet
Propulsion Laboratory. Dr. Gunapala has authored over
300 publications, including 13 book chapters. He holds
twenty-two U.S. patents.