Development of gallium nitride-based power electronic devices using plasma-assisted molecular beam epitaxy

This thesis work presents a comprehensive study on the development of GaN-based power electronic devices. The hands-on research on GaN compound semiconductors includes thin film growth, material characterization, device fabrication, and device characterization using state-of-the-art semiconductor processing equipment and characterizing tools. High-quality GaN films grown by plasma-assisted molecular beam epitaxy (PAMBE) are used for the fabrication of GaN-based field-effect transistor (FET) devices such as metal semiconductor FET (MESFET) and high electron mobility transistor (HEMT). In order to investigate the GaN-based FETs, theoretical principles, processing conditions, and characterization skills of the ohmic and Schottky metal contacts are discussed. The present work especially focuses on the reduction of power losses in GaN-based FET devices. For the first time, the PAMBE-based selective-area growth (SAG) technique is demonstrated to improve the properties of the ohmic contacts for n-GaN and AlGaN. Employing this technique, high-performance GaN MESFETs and HEMTs are fabricated and characterized.