Leak current in high resistive GaN buffer layer and its light responsiveness

We observed unique light responsiveness in HR GaN leak current, in which the current was drastically reduced under LED illumination of 2.65 eV or lower photon energy. Free carrier excitation by the illumination and consequential electron capture into the electron traps would rationalize the phenomenon. The threshold energy in our measurement was well associated with the carbon related very deep electron trap reported elsewhere (P. B. Klein et al., Appl. Phys. Lett. 79, 3527 (2001) [3]). Observation of this phenomenon provides us a very simple way to characterize both the HR GaN resistivity and the concentration of electron traps in the GaN buffer simultaneously. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)