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 Ec-150 meV and Ec-250 meV were observed, and their capture cross-sections (σT) were estimated to be 2.0x10-18 cm2 and 1.1x10-17 cm2, 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 N2 ambient after hydrogen treatment due to the reduction in dislocation density.