Defect-induced lateral chemical heterogeneity at Ni/GaN interfaces and its effect on the electronic properties of the interface

Scanning photoemission microscopy (SPEM) has been used to investigate the effect of morphological defects in GaN films grown on a 6H-SiC substrate on the composition and electronic properties of Ni/GaN interfaces in the temperature range of 25-600 degreesC. The SPEM imaging and spectroscopy identified a direct relation between the defects and the development of spatial heterogeneity in the interfacial composition, best pronounced after moderate annealing at 300 degreesC. The Schottky barrier height measured at these heterogeneous interfaces changes with advancement of the Ni-GaN reaction at elevated temperatures but exhibits negligible spatial variations. (C) 2001 American Institute of Physics.