Evaluation and Vacuum Stability Tests of Silicon Radiation Detectors

Tests have been carried out on a group of commercially available silicon radiation detectors of both diffused junction and surface barrier types. Measurements were made of reverse current and RMS noise level as a function of applied bias voltage in air and vacuum, alpha particle pulse height and energy resolution, and thickness of the sensitive surface dead layer. Long term stability was evaluated for samples in air and in vacuum by periodic measurements of reverse current, RMS noise voltage, and the pulse height and energy resolution for 5.8 Mev alpha particles. The samples in the vacuum tests were maintained at rated bias voltage and a pressure of approximately 10-6 Torr continuously for a period of six months. Only minor changes were observed in the performance characteristics of the devices. This work was sponsored by the Aeronautical Research Laboratory of Wright-Patterson Air Force Base, Office of Aerospace Research, United States Air Force.