Improved Gallium Nitride and Aluminum Nitride Electronic Materials

摘要

This report describes the results of a three year program to improve the qualityof Group III nitride electronic materials. The effort was directed toward understanding and controlling surface-reactive chemical paths toward the growth of GaN. We demonstrated low temperature synthesis of GaN from trimethyl gallium and ammonia by two techniques: a two-step process using atomic hydrogen and electron beams, and a single step process using only an electron beam. The electron beam activation made it possible to grow GaN in patterns. Several novel tools for the growth and processing of semiconductor materials resulted from this work. (1) A liquid N2-cooled reflector source of atomic hydrogen was developed for chemical activation and reactive cleaning of semiconductor surfaces. (2) An electron beam was used to stimulate the GaN synthesis reaction, providing a tool for activation of growth reactions which is an alternative to ion beams. These techniques were particularly effective in removing carbon associated with the methyl radical. In a parallel effort we carried out cathodoluminescence and infrared reflectance studies of GaN, AlN, superlattices, heterostructures with related wideband materials, providing information on the material defects and structure. We developed a model which allows the extraction of structural information of the component materials from infrared reflectance measurements near the restrahlen region. jg.