蓝宝石上GaN基多层膜结构椭偏研究  

Investigation of GaN-based multilayer structure films on sapphire substrate by spectroscopic ellipsometry

作　　者：杜江锋[1] 赵金霞[1] 罗谦[1] 于奇[1] 夏建新[1] 杨谟华[1] 

机构地区：[1]电子科技大学微电子与固体电子学院电子薄膜与集成器件国家重点实验室,四川成都610054

出　　处：《功能材料》2010年第5期878-880,共3页Journal of Functional Materials

基　　金：国家重点基础研究发展计划(973计划)资助项目(513270408);国家自然科学基金资助项目(60576007)

摘　　要：对InN/GaN/Al2O3和Ga2O3/GaN/Al2O3多层膜结构进行了椭圆偏振光谱研究。所有GaN样品均采用MOCVD工艺在蓝宝石(Al2O3)衬底上生长所得。应用多层介质膜模型,在300～800nm测试波长范围内拟合得到了样品各层厚度和折射率色散关系,并与GaN单层膜色散关系相比较,分析了各层膜之间对自身折射率的影响。研究结果表明,InN和Ga2O3表面均存在一个粗糙层,采用有效介质近似模型可使拟合结果更为准确;相对于GaN单层膜结构,InN薄膜使其下面的GaN层折射率明显增大,这应与界面层态密度有关;而在300～400nm测试范围内,Ga2O3折射率出现反常色散现象,InN消光系数亦产生了一个强的吸收峰,这则可能与GaN层在360nm左右存在的一个强吸收(Eg≈3.4eV)有关。The InN/GaN/Al2O3 and Ga2O3/GaN/Al2O3 multilayer structure films are investigated by spectroscopic ellipsometry （SE）.All the gallium nitride （GaN） samples are grown on c-plane sapphire substrate by metalorganic chemical vapor deposition （MOVCD）.The thickness and the optical constant spectra of the multilayer structures are obtained in the spectral range of 300-800nm by using the multilayer structure model.The influence of the interface state between layers on the refractive index is also analyzed through comparing with the GaN single layer.The measurement results indicate that a surface roughness layer is existent and can make the simulated results more exactly by using effective medium approximation （EMA） model.The refractive index of the GaN layer under the InN thin films is obviously larger than the GaN single layer,which is related with the interface state between the GaN and InN layer.A anomalous refractive phenomenon of Ga2O3 layer appeares in 300-400nm range,and the reason is probably interrelated with the strong absorbance of GaN layer in this wavelength range.

关 键 词：GAN 椭圆偏振光谱 INN GA2O3 

分 类 号：O484.5[理学—固体物理] TN304.23[理学—物理]