In this work, we prepare porous Si substrates via anodic etching process. The etching parameters such as time and current would be optimized for the best porous substrate, which is defined by having ...high porous density. The estimated average of porous density of the substrate is determined through the observation via scanning electron microscopy (SEM). After that, a thin GaN film is deposited onto the best porous Si substrate, using RF-sputtering machine. The grown layer is then will be characterized by photoluminescence (PL), X-ray diffraction (XRD) and Hall-effect measurements. As a comparison, we also grow and characterize a thin GaN on non-porous Si substrate, with the adoption of AlN buffer layer.
In this work, porous GaN was prepared by UV assisted electrochemical etching method. This method was employed in this work due to several advantages such as low processing temperature, low structural ...damage, process simplicity, versatility and low processing cost. The sample is required to be connected to power supply and biased positive and ultra-violet (UV) illumination is used to assist in the generation of electron-hole pairs. The porous GaN structures fabrication and their quantitative structural characteristics study are based on mathematical morphology analysis by using the scanning electrons microscope (SEM) images. The quality of porous GaN quality can be carried out by performing a nondestructive investigation of its nanostructures which can be performed by adapting image analysis techniques to obtain rapid, objective and quantitative information.
Aluminum nitride (AlN) and high aluminum (Al) content aluminum gallium nitride (AlGaN) thin films were successfully grown on gallium nitride (GaN) layer by plasma-assisted molecular beam epitaxy ...(PA-MBE) system. The films were deposited on Si 111 substrate. A systematic study and optimization of the growth conditions was performed in order to grow AlN and AlGaN layers on GaN films. Epitaxial growth of GaN has been demonstrated to be feasible for substrate temperature (800°C and 850°C) which depends on a Ga/nitrogen flux ratio. The absence of cubic phase GaN buffer layer for both samples has shown that this layer possessed hexagonal structure. The AlN sample has a good optical quality as measured by the photoluminescence (PL) system.
PDF