A DEEP-LEVEL TRANSIENT SPECTROSCOPY VARIATION FOR THE DETERMINATION OF DISPLACEMENT THRESHOLD ENERGIES IN GAAS

The deep-level transient spectroscopy (DLTS) method is optimized for the observation of radiation damage in semiconductors. A new isothermal variation of the technique is applied to the study of displacement defects in GaAs in order to determine threshold energies and displacement cross sections. A pronounced anisotropy is found for the threshold energy. A linearly increasing displacement probability function is shown to properly model the displacement cross section in [100] direction, as compared with the [111] direction which requires only a simple step function. Anisotropy leads to a tailing off in the displacement cross section at energies below an ''effective'' threshold of about 15.5 eV in the [100] direction, indicating that the [111] direction is more sensitive to displacement damage than the [100] direction. Differences in the damage between these two directions are as large as a factor of 2.