Thermoelectric voltage spectroscopy for studying compensation in semi-insulating wide energy band gap materials

A new method, thermoelectric voltage spectroscopy (TEVS), is demonstrated for the study of deep levels and compensation. Thermally stimulated conductivity (TSC) and thermoelectric emission spectroscopy (TEES) results are also shown for comparison. In TEVS, the thermoelectric voltage across a sample is measured as a function of the temperature, during the thermal stimulation of electron and hole traps. The TEVS voltage shows steps that reflect (1) the change of the electron and hole quasi-Fermi levels due to detrapping and (2) the trap type, whether electron or hole. A simple product rule holds between the TEVS voltage, TSC current, and TEES current, when identical trap filling and heating are done. The combination of TSC and TEVS is a powerful way for studying compensation and deep levels in semi-insulating wide energy band gap materials. (C) 1999 Elsevier Science Ltd. All rights reserved.