Thermally stimulated current trap in GaN

A thermally stimulated current peak, occurring at 100 K for a heating rate of 0.4 K/s, has been found in semi-insulating GaN grown by molecular beam epitaxy. This peak has contributions from two traps, with the main trap described by the following parameters: emission thermal activation energy E similar or equal to 90+/-2 meV, effective capture cross-section sigma similar or equal to 3+/-1X10(-22) cm(-2), and N mu tau similar or equal to 3+/-1 cm x 10(14) cm(-1) V-1, where N is the trap concentration, mu the mobility, and tau the free-carrier lifetime. This trap is much deeper than the typical shallow donors in conducting GaN, but shallower than any of the centers reported in recent deep level transient spectroscopy measurements. (C) 1996 American Institute of Physics.