Dr. Sarath Gunapala
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 profiles, relative humidity profiles, 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 artificial 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 6.1Å material system, has emerged as a fertile ground for the development of new solid-state devices. The flexibility 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. Gunapala is from the NASA Jet Propulsion Laboratory at California Institute of Technology. He is the director of Center for Infrared Sensors at Jet Propulsion Laboratory. Dr. Gunapala has authored over 250 publications, including several book chapters on QWIPs, and holds twenty two patents. He is a SPIE fellow.
Jet Propulsion Laboratory, 4800 Oak Grove Drive, California Institute of Technology, Pasadena, CA 91109, USA