Amorphous Germanium Contacts on Germanium
Gamma-ray Detectors
Ethan Hull
Tuesday, February 24, 2004
11:00 AM
Building 151, Room 1209 (Stevenson Conference Room)

Abstract:
Amorphous germanium technology can be used to fabricate rectifying contacts on germanium gamma-ray detectors.   These contacts form when a layer of amorphous germanium is deposited onto a crystalline germanium surface.   These contacts can form both hole and electron injection barriers.   This contact technology lends itself to the relatively simple fabrication of very fine electrode features.   This makes amorphous germanium contacts ideal for highly segmented detectors such as orthogonal strip germanium detectors used for gamma-ray imaging.   During the last year, a program has been started at LLNL to better understand amorphous germanium contacts.   Over 200 sample-test detectors and 1 large area imaging detector have been fabricated with amorphous germanium contacts to evaluate the potential of the technology.   The performance of the detectors is evaluated as a function of operating temperature, bias voltage, and fabrication parameters.   When fabrication techniques are optimized, the amorphous germanium contact appears to be capable of withstanding much higher electric fields than earlier work implied.   The data taken has prompted the identification of solid state physics models explaining the rectification properties of these contacts.