Gas-source MBE growth of GaN films using tertiarybutylhydrazine as a nitrogen precursor

Tertiarybutylhydrazine(TBHy) is one of the alternative nitrogen sources to ammonia. We investigated growth behavior of gas-source MBE grown GaN epilayers using TBHy by RHEED. It was found that the nitridation of sapphire surface occurred under TBHy irradiation at 900 degreesC above 10 min. GaN firms with crystal phase of hexagonal GaN and cubic GaN can be obtained, which depended growth conditions. Cubic phase GaN was formed by increasing the TBHy pressure (V/III ratio) as well as the increase of the substrate temperature. It is considered that some of pyrolysates which generated by thermal decomposition of TBHy on the growing surface may contribute to the growth of cubic phase. GaN grown on a low-temperature GaN buffer layer with a substrate nitridation had smoother surface than that without a substrate nitridation.