AlGaN/GaN HEMTs on epitaxies grown on composite substrate

In this paper, are presented the first results obtained from AlGaN/GaN HEMTs devices processed on both MBE and MOCVD epitaxial structures grown on "composite" substrates. These substrates are based on innovative structures in which a thin Si or SiC single crystal layer is transferred on top of a thick polycrystalline SiC wafer with a thin SiO2 intermediary insulating layer. The fabrication of the transistors is based on the process flow developed by "TIGER" for HEMT epitaxy on SiC bulk substrates. The obtained results show the capabilities of such composite devices, providing HEMT device electrical and small signal microwave performance similar to those obtained currently on bulk single crystal SiC substrates. The composite substrate approach appears as very promising for applications requiring low cost microwave power devices, such as mobile communications.