(Invited) Halide Vapor Phase Epitaxy for b- and a-Ga2O3 Power Electronics Devices

Abstract

Monoclinic b-Ga2O3 and rhombohedral a-Ga2O3 have recently emerged as promising materials for “ultrawide” bandgap electronics for next-generation high voltage lateral and vertical power switching devices, thanks to their large bandgaps (4.9eV and 5.3eV, respectively), high expected critical breakdown fields (8MV/cm and 10MV/cm, respectively), and their correspondingly large high voltage and high frequency Baliga figures of merit (FOMs). These large FOMs ultimately translate to higher efficiencies for high power (>1kW) switching devices, which will enable more compact, higher performing power electronics systems. In order to realize the high voltages required for the most demanding applications, further development of epitaxial growth techniques which can produce thick Ga2O3 films is required. Halide vapor phase epitaxy (HVPE) is a scalable and inexpensive growth technique which currently appears to be well positioned to address such a need. Kyma Technologies has developed a low-cost HVPE reactor for the growth of thick Ga2O3 films which boasts high growth rates and smoothness while simultaneously being able to be lightly and controllably doped with Si and free of carbon. The reactor has been configured to grow both b-Ga2O3 and a-Ga2O3, and in this talk we will outline our recent growth results from both. Effects of substrate preparation, epi-readiness, and growth conditions on epilayer quality as well as on the corresponding Schottky barrier diode device performance will be presented.