Characterisation of epitaxial SiC Schottky barriers as particle detectors

摘要

Epitaxial SiC devices have been tested as radiation detectors for minimum ionising particles. The devices used are based on a commercial 4H-SiC epitaxial n-type layer deposited onto a 4H-SiC n~+ type substrate wafer doped with nitrogen. Single-pad Schottky contacts have been produced by deposition of a 1000-A gold film on the epitaxial layer using a lift-off technology and ohmic contacts have been deposited on the rear substrate side. The capacitance-voltage characteristics have been measured to determine the net effective doping in the space charge layer and the maximum active thickness of the devices. The measurements showed possible non-uniformity in the net doping of the epitaxial layer. The charge collection efficiency (CCE) has been tested by means of a 0.1 mCi ~(90)Sr beta-source. A 100 percent CCE is measured at the maximum active thickness, which is achieved above approximately 400 V The charge signal of the SiC devices is stable and reproducible, with no evidence of priming or polarisation effects, due to the high crystalline quality of the epitaxial layer.