Electrical measurements on electron irradiated n-and p-type GaAs

Abstract

Hall effect and resistivity measurements have been made on undoped n-type and Cd-doped p-type GaAs crystals irradiated with electrons at 287°K. For 1 MeV irradiations, the dose dependence of carrier removal and mobility in n-type suggests that a defect energy level at E _c-0.1±0.015 eV was introduced by irradiation and was the upper level of a doubly charged acceptor. A donor level was also found in n-type at approximately E _c − 0.20 eV, and deeper acceptor levels were also introduced. In p-type a similar study located a radiation introduced level at E _v +0.1 ± 0.015 eV, which could be a singly or doubly ionized donor. Measurements of the carrier removal rate in p-type as a function of beam energy were in good agreement with those previously reported for n-type, thus confirming the displacement energy of 17–18 eV. It is suggested that the majority of displacement events gave rise to electrically active defects.