Growth and photoluminescence for undoped and N-doped ZnO grown on 6H-SiC substrate

Growth and photoluminescence (PL) spectra of undoped and N-doped ZnO grown on 6H-SiC substrate by plasma-assisted molecular beam epitaxy (P-MBE) method were especially studied. Compared with PL spectrum of undoped ZnO, a broadening of near-band-edge (NBE) emission was observed in N-doped samples at room temperature. The low-temperature (5 K) PL spectrum confirmed that some acceptor levels associated with N doping were presented in the N-doped ZnO sample. The NBE emission of undoped and N-doped ZnO samples grown on 6H-SiC showed a small blue-shift compared with that grown on Al2O3, it was relate to the change of band gap caused by stress. The intensity of dominant NBE emission from ZnO films grown on 6H-SiC is stronger and the FWHM is smaller than that grown on Al2O3 substrate. The deep-level emission can be observed on both samples, but the intensity ratio of NBE to deep-level emission is larger for ZnO samples grown on 6H-SiC.