Current-Voltage Characteristic of Semi-Insulating GaAs, with Trap-Filling Effect

A detailed investigation of current-voltage (I- V)characteristics of semi-insulating GaAs sample was performed in the vicinity of room temperature. The sample with 300 K resistivity of 2 x 10$\text{}^{7}$ Ω cm was supplied with guard-ring electrodes which allowed the elimination of surface currents. The observed characteristics started with an ohmic part which was followed by a superlinear current on voltage dependence. At a threshold voltage V$\text{}_{th}$ which corresponds to the electric field of about 2 kV/cm the current increased abruptly by a few orders of magnitude. The value of V$\text{}_{th}$ increased with the temperature. It is proposed that the observed shape of the I-V curve is caused by the filling of the EL2 level with injected electrons heated by the electric field.