常压MOCVD生长Ga2O3薄膜及其分析

以去离子水(H₂O)和三甲基镓(TMGa)为源材料,用常压MOCVD方法在蓝宝石(0001)面上生长出β-Ga₂O₃薄膜.用原子力显微镜(AFM)、X射线衍射(XRD)以及二次离子质谱(SIMS)实验表征Ga₂O₃外延膜的质量.在X射线衍射谱中有一个强的Ga₂O₃(102)面衍射峰,其半峰全宽(FWHM)为0.25°,表明该Ga₂O₃外延膜是(102)择优取向.在二次离子质谱中除了C、H、O和Ga原子外,没有观测到其他原子.

Ga2O3 Thin Films Grown on Sapphire by Atmospheric Pressure MOCVD

Gallium oxide(Ga₂O₃),a wide direct-gap semiconductor(E_g≈4.9 eV),has recently attracted interests as a new material for a gas sensor,transparent conductor,luminescent phosphors,solar cells,electronic and optoeclectonic applications.For Ga₂O₃ films growth,numerous deposition techniques including sputtering,electron-beam evaporation,molecular beam epitaxy(MBE),pulse-laser deposition(PLD),and metal organic chemical vapor deposition(MOCVD)have been employed.Among these techniques,MOCVD has many advantages for volume production and it has been proved to be excellent growth technique for Ⅲ-Ⅴs especially for the nitrides.Ga₂O₃ films used in this study were grown by a home-built vertical atmospheric pressure MOCVD system.Deionized water and trimethylgallium(TMGa)were used as the O and Ga sources,respectively,using nitrogen as the carrier gas.Typical growth conditions were as follows:chamber pressure was 103.3 kPa.The thickness of buffer layer is about 15 nm,growth temperature was 500℃,epilayer growth temperature was 700℃,and a total carrier gas flow rate was about 15000 sccm.The thickness of the Ga₂O₃ layer was about 2 μm.Ga₂O₃ epilayer characteristics were investigated by AFM,X-ray diffraction(XRD)and secondary ion mass spectroscopy(SIMS).The results of AFM indicated the Ga₂O₃ films grew up with columniation shape and the structure was relatively compact.The root mean square(RMS)roughness as determined by AFM(30 μm×30 μm)of the film surface was about 40 nm.The Ga₂O₃ grain size was about 30～40 nm determined by AFM.X-ray diffraction spectrum showed that the FWHM of(102)diffraction peak was 0.25°,which indicated the good quality of βGa₂O₃ film.The Ga₂O₃ grain size was calculated about 32 nm by Scherrer's formula,which was consistent with the result of AFM.The results of SIMS showed that the Ga₂O₃ epitaxial films had good purity.