||In this work, Nitridated b-LiGaO2 substrates have been used to grow nonpolar a-plane ZnO epitaxial films by a homemade thermal chemical vapor deposition. We control the quality of the films by adjusting the deposition position, growth temperature and oxygen partial pressure. The properties of the ZnO films was investigated by x-ray diffraction(XRD),|
scanning electron microscopy(SEM), atomic force microscopy(AFM), photoluminescence spectra(PL), Raman spectra(Raman) and transmission electron microscopy(TEM).
The results show that the crystal quality, surface morphology and optical properties of a-plane ZnO films are strongly related to the deposition position and growth temperature. It is also found that the surface roughness of the ZnO films gets more smoothly with increasing the oxygen partial pressure.
Up to now, ZnO films grown at 700℃ diplay the best crystal quality, the full width at half maximum values of (11-20)ZnO omega scan rocking curve is 0.5°. In comparison with above growth condition, it demonstrate better optical properties by shortening deposition position and increasing growth temperature to 750℃. Room temperature PL spectra exhibit a strong near band edge emission and a negligible green band. Furthermore, low temperature PL spectra is dominated by neutral donor-bound excitons and free electron-to-bound emission.
From the TEM selected area diffraction patterns and the XRD phi angle scan, the epitaxy relationship between ZnO and LGO is determined as LGO//ZnO and LGO//[10-10]ZnO. XRD omega-two theta scan and Raman spectra analysis are carried out to characterize the status of the strain in ZnO film is compressive, the reason is illustrate in detail.