Substrates and epitaxial deposition processes for Group III-nitride thin films and power device heterostructures

摘要

The methodologies, results, and status of investigations for the development of solvothermal, vapor-phase transport, and solution techniques for bulk crystal growth of large diameter GaN and AIN crystals are presented. This work is being driven by (1) the anticipated need for the initial homoepitaxy of ever-thicker GaN films having very low densities of both threading dislocations and unintentionally introduced, electronically important impurities for devices operating at high and very high load levels; (2) the desire to move from lateral to vertical device structures; and (3) recent results of near theoretical breakdown behavior and near system-level performance in vertical GaN diodes grown on GaN substrates. The choice of the substrate dictates the technique and process routes for the growth of Group III-nitride-based thin films and material device structures. Organometallic vapor-phase epitaxy is the commercial process route of choice for the growth of Group III-nitride films. A review of the precursor gases used in this technique, their stability in the growth reactor and reactivity with nitrogen-containing gases, and the choice of diluent for the growth of films of different nitrides is also presented.