Photoconductivity as a Function of Temperature in MOCVD Grown Gallium Nitride Films

Abstract

The optical absorption in gallium nitride (GaN) films was studied by photoconductivity (PC) spectroscopy at various temperatures. At all the measured temperatures, the photoconductivity per incident photon increases with photon energy hv from 1.8 eV to 3.0 eV approximately as exp(hv/E0). Surprisingly, the measured photoconductivity tail to the infrared becomes more pronounced in magnitude at lower temperatures. We suggest from the data that the photoconductivity is dominated by majority carriers, and that the quantum efficiency η for conducting electron and hole generation by across-gap excitation increases with increasing temperature.

Photocurrent decay in n-type GaN thin films

“…26 Furthermore, the steady state photoconductivity for across the gap photoexcitation increases with increasing temperature, 27 in contrast to the thermal quenching behavior observed for recombination at dislocations. It thus seems that recombination at dislocations is not a dominant recombination channel in undoped n-type GaN.…”