Scanning probe microscopy studies on the growth of palladium and nickel on GaN(0001)

Abstract

The performance of GaN-based devices, such as blue LEDs and laser diodes, relies on good metal-GaN contacts. However, little is known about the formation and properties of these contacts on the atomic scale. We have studied the initial stages of growth of Pd and Ni on the GaN(0001) surface using variable temperature UHV-STM. The atomic-scale STM images have been compared with tapping-mode AFM images and point I-V measurements using conductive AFM in order to correlate performance on nano-scale and micro-scale. The growth mode of the metals and formation of alloys and interfacial compounds have important consequences for the electrical contact behaviour. Systematic control of the deposition conditions is therefore crucial for the performance of the contacts. © 2010 IOP Publishing Ltd.