Formation of a quasi-neutral region in Schottky diodes based on semi-insulating GaAs

A model is developed for the electric field distribution beneath the Schottky contact in semi-insulating (SI) GaAs particle detectors. The model is based on a field-enhanced electron capture of the EL2 defect. The influence of the compensation mechanism in SI GaAs on the field distribution and leakage current density of the detectors is discussed. The detailed understanding allows a device optimisation.