Papers by Keyword: GaNAs

Abstract: This paper describes Transmission Electron Microscopy studies of the structural changes of GaN1-xAsx alloys grown by Molecular Beam Epitaxy at low temperatures on Al2O3 substrate. We found that by lowering the growth temperature increasing amount of As can be incorporated in GaN1-xAsx forming a single phase alloy. For the low As content a columnar growth of wurtzite structure is observed but for increasing As in the range of 0.170.75 the layer becomes amorphous. Increase in Ga flux at low growth temperature (about 200°C) leads to columnar alloys with As content >75% with a cubic structure. In addition to the structural changes monotonic change of the band gap is also observed with the As content in the alloy. The amorphous alloy is stable up to annealing at temperatures not higher than 600°C. Annealing at higher temperature leads to phase separation of GaAs:N and GaN:As confirmed by Z-contrast electron microscopy.

Abstract: Photoluminescence (PL) measurement shows an additional peak with stronger and broader emission at lower photon energy besides the energy band gap transition emission from GaNAs epilayer grown by MOCVD. This emission is assigned as nitrogen-nitrogen interstitial defect related emission. Effect of V/III ratio during the MOCVD growth on this defect related emission peak has been investigated. The combination of optimum V/III ratio during the MOCVD growth and post-growth rapid thermal anneal (RTA) can eliminate this defect emission peak and at the same time the GaNAs’ band gap emission has been greatly improved. The PL spectra contain a single, narrow, and high intensity GaNAs’ band gap transition emission after the RTA annealing. The optimum V/III ratio for growing the GaNAs films with N content < 3.5% is around 20.