OZARK INTEGRATED CIRCUITS INC — Department of Defense SBIR Phase I: N231-070

Description

Ozark IC has demonstrated year-long operation in LEO of a UV sensing solid-state SiC bipolar junction phototransistor that exceeds all the solicited specifications.  The phototransistor is both monolithic and isolated such that the SiC NPN that can be patterned into individually addressable pixels with micron scaled lithography. The ultrahigh current gain of the transistor produces an external quantum efficiency of 1000%, yielding an effective UVC sensitivity of 2A/W. The indirect bandgap of 4H-SiC produces a naturally occurring VISIR-blind cut-off of 360 nm.  The 40 nm spectral separation from VISIR produces a UVC/VIS sensitivity ratio of infinity, with a dark current measured in the sub-pA range.  Operation of the device has been demonstrated from -180°C to 400°C.  Spaceborne heritage includes 1 year of continuous operation in LEO with indirect exposure to atomic oxygen. Vibroacoustic heritage includes survival through launch, ISS deployment, and recovery. Ozark IC proposes to improve the utility of the device through reimplementation using an alternate thin-film process. The process will enable monolithic inclusion of additional isolated devices including a complementary PNP transistor, NJFET, diode, and resistor. Expansion of the available devices will enable UV-detecting very large scale integrated (VLSI) circuits be realized, such as focal plane arrays (FPAs).