Fabrication and Characterization of Gallium Nitride Based Diodes

Abstract

This dissertation describes research to the fabrication and characterization of Gallium nitride (GaN) based diodes. GaN is considered to be probably one of the most significant semiconductor material ever discovered dissertation describes research to the fabrication and characterization of Gallium nitride (GaN). Because of its direct wide bandgap and outstanding electric properties, GaN is widely used in solid state lighting applications and considered as an alternative to Silicon in power electronics devices. High performance GaN based Schottky diodes were fabricated using n- bulk GaN substrates synthesized by Hydride Vapor Phase Epitaxy (HVPE) process. Full back ohmic contact was deposited on the N face and circular Schottky contacts on the Ga face. The Schottky diodes showed excellent forward and reverse bias characteristics, which resulted in a high figure of merit (FOM). We have also fabricated GaN Schottky diodes on n- epilayer/ n+ bulk GaN structure, where the epilayers were deposited using Metal-Organic Chemical Vapor Deposition (MOCVD) on HVPE grown substrate. The devices showed very high breakdown voltages. Electrical measurements such as current-voltage (I-V) and capacitance-voltage (C-V) were used to extract ideality factors, series resistance and other important parameters from the diodes. Raman spectroscopy was also carried out to determine the average junction temperature of the commercial ultraviolet (UV) light emitting diodes (LEDs).