Study On The Synthesis And Property Of GaN Nanowires And Films

GaN is a kind of semiconductor material with wide band gap, which has favorable material properties, such as high electron mobility and very high thermal conductivity. In recent years, GaN has attracted more and more attention, mainly due to its promising applications in short-wave light-emitting devices, photodetectors, anti-radiation, high frequency and high power electronic devices. However, because it is difficult to grow large bulk single crystal of GaN, the synthesis of one-dimensional GaN nanomaterials and GaN films is important to the development of GaN-based devices. In this dissertation, GaN nanowires and GaN film were systematically synthesized and investigated. The main results are as follows.1. In tubular furnace, high quality GaN nanowires were synthesized at 1000°C with Pt as catalyst, Ga₂O₃ and NH₃ as sources. Field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and PL spectra were used to characterize the samples. The results indicated that the products were straight and smooth GaN nanowires with the diameters ranging from 50nm to 100nm and lengths up to several tens of microns. High quality GaN nanowires were single crystal with hexagonal structure, good optical quality and few defects. They were suggested to grow along [100] direction by VLS mechanism.2. GaN nanowires were directly synthesized on Si substrate with Ga₂O₃ as Ga source and NH₃ as N source, without using any catalyst. Under the same experiment conditions, GaN nanorods were synthesized on quartz substrate. The observations by FESEM, XRD and HRTEM indicated that the structure of GaN nanowires obtained was hexagonal, rough in surface and with a few defects. Their diameters were about 100nm, and lengths can be up to several hundreds of microns. The nanowires were suggested to grow along [100] derection by VS mechanism. The diameter of the nanorods was about 200nm. With the length in the range of several hundreds of nanometers to 2μm, the GaN nanorods can be explained by VS mechanism for growth.3. With Ga₂O₃ and Ga as Ga source, and NH₃ as N source, GaN films were synthesized on Si wafer in tubular furnace. The observations by FESEM, XRD and EDS indicated that the GaN films were formed of GaN crystal grain with hexagonal structure, having high quality with smooth surface and few defects.