Deep level transient spectroscopy in plasma-assisted molecular beam epitaxy grown Al0.2Ga0.8N/GaN interface and the rapid thermal annealing effect

We investigated deep-level traps formed in Al0.2Ga0.8N/GaN heterostructures grown using plasma-assisted molecular beam epitaxy and by performing deep level transient spectroscopy (DLTS). Two electron traps with activation energies of E-c-150 meV and E-c-250 meV were observed, and their capture cross-sections (sigma(T)) were estimated to be 2.0x10(-18) cm(2) and 1.1x10(-17) cm(2), respectively. Different behaviors in the dependence of DLTS on filling pulse length confirm that the traps originated from N vacancies and dislocations. The amplitude of the dislocation-induced DLTS signal was reduced significantly by high-temperature rapid thermal annealing under N-2 ambient after hydrogen treatment due to the reduction in dislocation density. (c) 2010 American Institute of Physics. [doi:10.1063/1.3491798]