Proceedings Article | 29 April 2009
Proc. SPIE. 7307, Airborne Intelligence, Surveillance, Reconnaissance (ISR) Systems and Applications VI
KEYWORDS: Staring arrays, Short wave infrared radiation, Indium gallium arsenide, Imaging systems, Cameras, Sensors, Germanium, Electrons, Silicon, Quantum efficiency
There are few choices when identifying detector materials for use in the SWIR wavelength band. We have exploited the
direct-bandgap InGaAs material system to achieve superior room temperature (293°K) dark current. We have
demonstrated sensitivity from 400nm through 2.6um with this material system and thus provide the opportunity to sense
not only the visible, but also the J-band (1.25um), H-band (1.65um) and K-band (2.2um) windows. This paper discusses
the advantages of our hybridized CMOS-InGaAs material system versus other potential SWIR material systems.
The monolithic planar InGaAs detector array enables 100% fill factor and thus, high external quantum efficiency. We
have achieved room-temperature pixel dark current of 2.8fA and shot noise of 110 electrons per pixel per second. Low
dark current at +300K allows uncooled packaging options, affording the system designer dramatic reductions in size,
weight (cameras <28grams), and power (<2.5W). Commercially available InGaAs pin arrays have shown diode lifetime
mean time between failures (MTBF) of 1011hours for planar InGaAs detectors1, far exceeding telecom-grade reliability
requirements. The use of a hybrid CMOS-InGaAs system allows best of breed materials to be used and permits efficient, cost-effective,
volume integration. Moreover, we will discuss how the InGaAsP material system is compatible with CMOS monolithic
integration. Taken together, these advantages, we believe, make InGaAs the obvious choice for all future SWIR
systems.
