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

Scanning photoemission microscopy (SPEM) has been used to investigate the e ffect of morphological defects in GaN films grown on a 6H-SiC substrate on the composition and electronic properties of Ni/GaN interfaces in the tempe rature range of 25-600 degreesC. The SPEM imaging and spectroscopy identifi ed a direct relation between the defects and the development of spatial het erogeneity in the interfacial composition, best pronounced after moderate a nnealing at 300 degreesC. The Schottky barrier height measured at these het erogeneous interfaces changes with advancement of the Ni-GaN reaction at el evated temperatures but exhibits negligible spatial variations. (C) 2001 Am erican Institute of Physics.