NASA STTR 2004 Solicitation


RESEARCH SUBTOPIC TITLE:Space Science Sensors and Instruments
PROPOSAL TITLE:GaN Based UV Sensors for Earth Resources Management

NAME: TechnoVentures, LLC NAME:University of Maryland
ADDRESS:17 Saddlerock Court ADDRESS:AV Williams Building
CITY:Silver Spring CITY:College Park
STATE/ZIP:MD  20902-1611 STATE/ZIP:MD  20742-5141
PHONE: (301) 593-8002 PHONE: (301) 405-7187

J Ari   Tuchman

TECHNICAL ABSTRACT ( Limit 2000 characters, approximately 200 words)
This work represents the exploitation of a unique method of crystal growth – constrained epitaxy (CE) – in the manufacture of low-noise, multi-color UV sensors. The sensors developed here are based on the GaN/AlGaN materials system and are sensitive in the wavelength range from 250-400nm. Target responsivities are > 0.1 A/W throughout the spectral interest range. The first arrays produced under phase 1 were sensitive both to 285 and 315 nm simultaneously. Multicolor sensitivity improves background noise rejection and provides much more detailed analysis of atmospheric aerosol scattering. Noise is dominated by diode reverse leakage and is less than 10-9A/cm2. The CE manufacturing process is enabled by the recognition that surfaces on which radiation sensitive materials are grown cannot be exposed to plasma etch effluents. To overcome this limitation, a dielectric lift-off-lithography process was developed. In this process, the growth surfaces only come in contact with organic solvents and photosensitive plastics during manufacture. Initial results were obtained on a 10 x 10 diode array. In subsequent work, we intend to produce 100 x 100 arrays. In addition, it the range of attainable spectral sensitivities will be mapped out by studying the range of achievable AlGaN stoichiometries that are practically attainable.

POTENTIAL NASA COMMERCIAL APPLICATIONS ( Limit 1500 characters, approximately 150 words)
Within NASA, there are several possible applications. In addition to the astrophysics observatory, UV photo-detectors can be used in surveillance, rocket plume tracking and plume sensing, combustion and flame-out detection, and other similar applications. The high signal-to-noise ratio and the fast response time accomplished by UV photodetectors make them especially useful for NASA and several defense applications in extremely harsh environments. The characteristics that make UV photodetectors suitable for NASA applications also benefit many industrial and scientific applications. Several applications in environmental monitoring and control use UV sensors. For example, UV based systems can detect ozone, sulphur dioxide, and benzene. Since many of these sub-system use an excimer laser (at 248 nm) as a source, it is important to use a “solar blind” detector in this application. Companies such as Honeywell are also evaluating UV detectors for furnace control functions. In addition, UV spectroscopy plays an important role in several medical and scientific applications.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS ( Limit 1500 characters, approximately 150 words)
Most of the applications listed above are of high commercial value. Of course, environmental effluent monitoring and inspection of geological formations for oil exploration is primarily a commercial application are significant targets of opportunity. Furnace control systems and flame imaging of commercial jet engines are also important commercial applications.

Form Printed on 02-02-06 17:38