Optical deep-level transient characterisation of gamma-irradiated semi-insulating gallium arsenide

A unique optical deep-level transient conductance spectroscopy (ODLTCS) technique has been employed for studying undoped semi-insulating (SI) GaAs material. In the undoped SI GaAs, the Fermi-level first shifts towards gamma irradiation of the conduction band at low γ fluence and then towards the valence band at high γ fluence. Similar conclusions have been derived from electron-paramagnetic resonance (EPR) measurements on the ionised ASGa concentration.