Development of AlGaN/SiC Epitaxial Wafers

We propose to develop AlGaN/SiC epitaxial wafers to be used as substrates for III-V nitride homoepitaxy. Lack of GaN and AIN substrates for homoepitaxy limits the development of electronic devices based on III-V nitrides. TDI has demonstrated that thin (~0.5 Sun) high quality GaN layers can be grown on silicon carbide wafers by hydride vapor phase epitaxy (HVPE). These structures, consisting of a thin GaN layer on SiC wafers, are called GaN/SiC epitaxial wafers. It was shown that GaN/SiC epitaxial wafers are good substrates for subsequent GaN homoepitaxial growth. SiC, as initial substrate material, provides excellent heat removal from device structure, gives cleaving possibility, and allows one to develop electronic devices with vertical current-flow geometry. Recently, we applied HVPE technique to AIN and AlGaN growth on SiC wafers. These results open the opportunity to develop AlGaN/SiC epitaxial wafers with A1N concentration ranging from 0 to 100%. In this case, composition of AlGaN epitaxial wafer will be controlled to minimize stress in the desired device structure. Another breakthrough has been achieved on HVPE growth of insulating GaN. The goal of Phase I is to prove the concept and demonstrate GaN/SiC, AlN/SiC, and Al0.5GaO.5N/SiC epitaxial wafers. We will demonstrate both conducting GaN/SiC epitaxial wafers and GaN/SiC epitaxial wafers with highly resistive GaN grown on semi-insulating SiC substrates. Test samples will be delivered. In Phase II, we plan to develop a multi-wafer production process for 2-inch AlGaN/SiC epitaxial wafers with reduced dislocation density.