Growth of GaN films on silicon (111) by thermal vapor deposition method: Optical functions and MSM UV photodetector applications

In this study, gallium nitride (GaN) films were grown on n-Si (1 1 1) substrate by thermal vapor deposition method in quartz tube furnace for different growth duration. Gallium metal mixed with GaN powder and aqueous ammonia (NH3) solutions were used as sources of Ga and N. Structural, elemental, and optical characterizations were carried out using various techniques in order to investigate the properties of the films. Scanning electron microscopy images showed that the films surface have self-textured morphology, which was introduced during the growth process. Moreover, further deposition resulted in the formation of heterogeneous film. X-ray diffraction (XRD) measurements reveal in all samples a typical diffraction pattern of hexagonal GaN wurtzite structure. Raman spectra demonstrated redshifts in E-2-high with increasing deposition time due to tensile stress inside the GaN films, confirmed by XRD. The photoluminescence spectra of the films demonstrated strong near band edge emission at about 363 nm. The fabricated GaN films based metal-semiconductormetal (MSM) UV photodetector shows a contrast ratio of similar to 240-40 at +5 V and responsivity in the range of 0.28-0.01 A/W for the UV photodetectors. This study shows the possibility of synthesizing GaN films on Si wafers at low-cost and has potential applications in UV photodetection. (C) 2013 Elsevier Ltd. All rights reserved.