Plasma Assisted Molecular Beam Epitaxy Grown GaN Nanowires On Si (211) Substrates for UV Sensing Applications

III-Nitrides have attracted significant research interest in the recent years owing to their wide range of applications. In this study catalyst free plasma assisted molecular beam epitaxy growth of GaN nanowires on Si (211) substrates for UV sensing applications is reported. The GaN nanowires were characterized using field emission scanning electron microscopy and photoluminescence spectroscopy. The field emission scanning electron microscopy results indicated that the nanowires are dense and preferentially oriented. The peak observed at around 3.42 eV in the photoluminescence spectra corresponding to GaN band edge emission confirms that the nanowires are of high optical quality. For UV sensor measurements two Indium contacts were soldered on the surface of the nanowires and resistance between the ohmic contacts was measured as a function of time. The sensor response was measured as the ratio of change in resistance upon exposure to UV to the resistance in air. GaN nanowires showed a response of 2.2% upon exposure to UV with a fast response time. Through this work we show that GaN nanowires on Si (211) substrates are suitable candidates for UV sensing applications.