Prompt charge collection in gallium-arsenide diodes struck by energetic heavy ions

Charge collection was measured as a function of reverse-bias voltage on GaAs Schottky-barrier diodes bombarded with heavy, energetic ions. Ion species included in the study were copper (57 MeV), chlorine (62 MeV), oxygen (18 MeV), and, to establish a baseline for comparisons, 241Am-decay alpha particles (5.4 MeV). Measurements of the drift component of collected charge are compared to funneling predictions based on the Hu and McLean-Oldham models. Results show that significant funneling occurs in these gallium arsenide diodes, in reasonable agreement with predictions for the light ions, but to a lesser extent than predicted by both models for the heavier ions. By comparing these results with data on silicon diodes published in the literature, gallium arsenide is shown to be less responsible to heavy ion strikes than silicon. This enhances the value of the gallium arsenide technology for systems required to operate in environments containing high-energy heavy ions, such as cosmic rays in the exoatmosphere. A corrective plasma screening factor has been added to the McLean-Oldham effective funnel length model to account for the reduced drift collection after heavy-ion strikes