Windowed growth of AlGaN/GaN heterostructures on Silicon 〈111〉 substrates for future MOS integration

A novel windowed growth technique that allows for the exposure of a smooth silicon surface for MOS circuitry between AlGaN/GaN HEMT layers has been developed. A sacrificial oxide based dielectric stack is used to protect regions of the silicon surface before growth by ammonia-MBE. SIMS analysis shows elevated oxygen impurity incorporation in the stress-relief layer, but controllable levels in the C-doped GaN buffer. A Hall mobility of 1.37 × 10 3 cm 2/Vs is measured in the AlGaN/GaN regions. AFM results show a RMS roughness of 0.12 nm on the silicon surface