Structural, Optical and Electrical Properties of InGaN Sputtered Thin Films

Abstract

InGaN films were successfully fabricated using radio frequency (RF) magnetron sputtering technique with a sputtering target of pure In and Ga metal alloys under a flow of nitrogen. Films were deposited on quartz substrates, with the ratio of In to Ga varied from 0.46 to 0.85 in the alloys. The structures and compositions have been studied using X-ray diffraction (XRD) and energy dispersive x-ray spectroscopy (EDX), respectively. Multiple crystallographic phases have been observed indicating phase segregation and inhomogeneous distribution of the metal compositions in the films. The existence of wurtzite structures has been observed in all samples, with the In percentage (y) in a crystalline phase calculated from the XRD being less than the total In percentage (x) in each film as determined by the EDX spectroscopy. The (0002) orientation has been observed in all films, and the (10-11) orientation has been observed for x = 0.46 and 0.70 only. The optical transmission and absorbance of the films were studied by the spectrophotometry technique, which indicate that the dominant phases in all samples are amorphous. Consequently, the corresponding optical bandgaps have been characterized. Hall Effect measurements were made in 0.55 T magnetic field at room temperature to characterize the electrical conductivity, free carrier concentration, and mobility.