MODIFIED EXPONENTIAL FIT OF OPTICALLY INDUCED TRANSIENT CURRENTS IN SEMIINSULATING SEMICONDUCTORS

In the original model for optical transient current spectroscopy for deep levels in semi-insulating GaAs it was assumed that the currents were due to release of electrons from traps in the depletion region of a reverse biased Schottky diode contact and their transit through the depletion layer. For the geometries normally used, a more realistic model involves processes in a neutral semiconductor. In this case retrapping effects are now shown to lead to a modified form of an exponentially decaying transient. Using an isothermal method of decomposition of the digitized transient into the decays due to separate deep levels it was found that a better fit is obtained using the new form, and anomalous activation energies are avoided.