Description: In this SBIR Program, Structured Materials Industries, Inc. (SMI) and partners are developing ultraviolet (UV) photodetection devices with high sensitivity, low noise and fast response time. The technical approach is based on nanowires of the wide bandgap semiconductor ZnMgO. The resulting devices will be blind to solar radiation, and have a tunable cut-off frequency which can be adjusted by the Mg content. The resulting photodetection devices will also be low-cost, and compatible with a wide range of device materials, including silicon substrates and silicon integrated circuitry. During Phase I, the SBIR team demonstrated technical feasibility of a simple process for fabricating the photodetectors from vertically aligned arrays of nanowires. These Phase I achievements enable low cost production of nanowire based photodetection devices, using standard microelectronic techniques. The Phase I results will ultimately enable high volume production of nanowire devices, on large area substrates, and enable integration with other microelectronic circuitry.

Benefits: NASA's interest in UV photodetectors includes spectroscopic analysis for planetary and atmospheric studies; temperature and composition analysis of young stars; and composition, density and temperature measurements of the interstellar medium. These missions require UV detectors and detector arrays with high sensitivity, low noise, fast response time and high spectral selectivity. Since these observations are frequently made from platforms operating above Earth's atmosphere (which absorbs UV), the photodetectors must also be small size, low mass, low power, and low cost to make the best use of limited payloads and NASA resources. Extended operation in space also requires the devices to be radiation resistance, temperature resistance, highly reliable and have long lifetime.

Photodetectors are used in a wide range of applications for commercial, industrial, scientific and military markets. Photodetectors based on wide bandgap semiconductor materials operate in the ultraviolet (UV) spectral range. UV photodetectors can be used in spectroscopy, optical communications and optical data storage. Because of their large bandgap, these detectors are blind to visible and solar radiation. Visible/solar blind UV photodetectors are useful for monitoring and detection of high temperature heat sources in ambient light, such as for flame detectors or for detecting the exhaust signatures of hostile aircraft and missiles.