Low Temperature Growth of Oriented Gallium Nitride using Pulsed Laser Deposition

Abstract

ABSTRACTOriented GaN has been successfully grown at low substrate temperatures (∼480°C) on a- and r-planes of sapphire, using the pulsed laser deposition process. We have examined the effects of several deposition parameters on film growth, including substrate temperature (∼50–500°C), ambient pressure (1×10−3 – 10 torr of NH3), and target material (Ga or GaN). The film deposition rate was typically ∼3–4 μm/hr. Film characterization was performed using x-ray diffraction (XRD), optical microscopy, x-ray photoelectron spectrometry (XPS), and atomic force microscopy (AFM). In the case of the Ga metal target, a plasma (∼500V) between the target and substrate was necessary to promote formation of the GaN phase. The ammonia ambient enhanced the nitrogen content in the films compared to vacuum deposition. In general, the GaN target yielded better quality films (smaller rocking curve widths and smoother film morphology) compared to the Ga metal target. These results suggest that pulsed laser deposition is a promising approach to fabricating high quality films of this potentially important semiconducting material.