论文部分内容阅读
With the solid phase reaction between pulsed-laser-deposited(PLD)ZnO film andα-Al_2O_3 substrate,ZnAl_2O_4/α-Al_2O_3 complex substrates were synthesized.X-ray diffraction(XRD)spectra show that as the reaction proceeds,ZnAl_2O_4 changes from the initial(111)-oriented singlecrystal to poly-crystal,and then to inadequate(111)orientation.Corresponding scanning electronmicroscope(SEM)images indicate that the surface morphology of ZnAl_2O_4 transforms from uni-form islands to stick structures,and then to bulgy-line structures.In addition,XRD spectra presentthat ZnAl_2O_4 prepared at low temperature is unstable at the environment of higher temperature.Onthe as-obtained ZnAl_2O_4/α-Al_2O_3 substrates,GaN films were grown without any nitride buffer usinglight-radiation heating low-pressure MOCVD(LRH-LP-MOCVD).XRD spectra indicate that GaNfilm on this kind of complex substrate changes from c-axis single crystal to poly-crystal as ZnAI204layer is thickened.For the single crystal GaN,its full width at half maximum(FWHM)of X-rayrocking curve is 0.4°.Results indicate that islands on thin ZnAl_2O_4 layer can promote nucleation atinitial stage of GaN growth,which leads to the(0001)-oriented GaN film.
The solid phase reaction between pulsed-laser-deposited (PLD) ZnO film and α-Al_2O_3 substrate, ZnAl_2O_4 / α-Al_2O_3 complex substrates were synthesized.X-ray diffraction (XRD) spectra show that as the reaction proceeds, ZnAl_2O_4 changes from the initial (111) -oriented singlecrystal to poly-crystal, and then to inadequate (111) orientation. Corresponding scanning electron microscope (SEM) images that the surface morphology of ZnAl_2O_4 transforms from uni-form islands to stick structures, and then to bulgy- In addition, XRD spectra presentthat ZnAl 2 O 4 prepared at low temperature is unstable at the environment of higher temperature. Onthe as-obtained ZnAl 2 O 4 / α-Al 2 O 3 substrates, GaN films were grown without any nitride buffer usinglight-radiation heating low-pressure MOCVD (LRH-LP-MOCVD). XRD spectra indicate that GaNfilm on this kind of complex substrate changes from c-axis single crystal to poly-crystal as ZnAI204layer is thickened. For the single crystal GaN, its full w idth at half maximum (FWHM) of X-ray rocking curve is 0.4 ° .Results indicate that islands on thin ZnAl_2O_4 layer can promote nucleation at initial stage of GaN growth, which leads to the (0001) -oriented GaN film.