InP:Fe and GaAs:Cr Picosecond Photoconductive Radiation Detectors

摘要

The dark current, impulse and square-pulse response measurements of photoconductive devices fabricated from two different types of materials, Gallium Arsenide with Chromium dopant (GaAs:r) and Indium Phosphide with Iron dopant (InP:Fe) are reported. These devices have been subjected to irradiation from the S-band Electron Linear Accelerator (LINAC) with an energy fo 100 MeV at room temperature. Fluence ranged between 10 to the 13th power and 10 to the 16th power electrons/sq cm. Dark current decreases with increasing fluence for the GaAs:Cr devices whereas InP:Fe shows an increase in the dark current. Both types of materials exhibit extremely fast impulse response after the irradiation. Electron mobility, drift velocity and response speed decrease with increasing fluence. Response speeds of < 100 ps are achieved by fast carrier relaxation in the semiconductor due to the introduction of trapping and recombination centers resulting from the irradiation damage. The GaAs:Cr, unlike the InP:Fe, more closely follows the longer square-pulse exhibiting non nonlinearity. All results are consistent with previously investigated neutron irradiated devices. (Thesis).