AlN/Si(100)上CVD SiC薄膜的光致发光谱

本工作用化学气相淀积方法在AlN/Si(100)复合衬底上生长SiC薄膜.外延生长过程中,采用C4H4和SiH4作为反应气源,H2作为载气.样品的X-射线衍射谱和拉曼散射谱显示,所得到的外延层为六角对称的SiC薄膜.俄歇电子能谱及X-射线光电子能谱的测量结果表明,在外延膜中存在来自衬底的Al和N元素.样品的光致发光测量显示,所有的样品均可在室温下观察到位于3.03eV和3.17eV处的发光峰,这分别相应于4H-SiC能带中电子从导带到Al受主能级之间的辐射跃迁和电子从N施主能级到价带之间的辐射跃迁,从而表明所得的外延薄膜的多形体为4H-SiC.

Photoluminescence Study of Epitaxial 4H-SiC Grown on AlN/Si ( 100 ) Complex Substrate by Chemical Vapor Deposition

Epitaxial 4H-SiC grown on AlN/Si(100) complex substrate by chemical vapor deposition(CVD) at the relatively low temperature was investigated.During the growth,ethylene and silane were used as the precursors and hydrogen as the carrier gas.The structural and optical properties of the epitaxial film were characterized by various methods.The results of X-ray diffraction(XRD) and Raman scattering show that the obtained epilayer is monocrystalline hexagonal SiC.By the Auger electron spectrum(AES),the thermal diffusion of Al and N from the AlN buffer layer to the SiC epitaxial layer was observed.Al and N were proved to be substitute for Si and C respectively in the SiC layer by the X-ray photoelectron spectrum(XPS).The room-temperature photoluminescence(PL) consisted with the Al acceptor level and the N donor level was observed at 3.03eV and 3.17eV,respectively.The obtained epitaxial SiC layer was thus proved to be 4H polytype.A PL peak corresponding to the recombination between the secondary conduction band minimum of 4H-SiC and the Si-vacancy acceptor level was also observed at 3.37eV.