Polarized XAFS study of Al K-edge for m-plane AlGaN films

摘要

Local structures around Al atoms in high-quality m-plane Al_xGa_(1-x)N films (x=0.32 and 0.58) deposited on m-plane GaN substrates by the NH_3 source molecular beam epitaxy method were investigated by Al K-edge X-ray absorption fine structure (XAFS) for the first time. XAFS spectra were measured using a linearly-polarized X-ray source from synchrotron radiation for three different directions; along the c-, a-, and m-axes. The interatomic distances along the a-axis are close to Ga-Ga distance in GaN, indicating that the local structures are strongly affected by GaN substrates. The localization of Al atoms was observed for the Al_(0.32)Ga_(0.68)N film.