engleski

Thermoelectric Effect Spectroscopy Measurements on Semi-Insulating GaN

A new, simplified set-up for the thermoelectric effect spectroscopy (TEES) especially suitable for film-on-substrate sample types was introduced. The temperature gradient along the sample was achieved here without additional heater. This set-up was then applied for measurements on the semi-insulating GaN, grown at sapphire substrate by a molecular beam epitaxy, in order to investigate deep level’ s (trap’ s) sign. Measured TEES currents were found negative at lower temperatures and positive at higher temperatures, indicating that shallower deep levels belong to electron traps, and deeper levels to hole traps. Deep traps were further characterized by using the thermally stimulated current (TSC) measurements and the simultaneous multiple peak analysis (SIMPA) analytical method. The shallowest observed electron and hole traps had activation energies Ec-0.09 eV and Ev+0.167 eV, respectively. Both hole and electron traps were found in relatively high concentrations causing compensation and high resistivity.

Thermelectric effect; deep traps; GaN

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