半导体氮化物AlInN的光学性质

Optical properties of AlInN thin films

测量了AlInN薄膜(包括InN和AlN)的透射和反射光谱,结合四层透射和反射模型得到AlInN的一系列变温光学性质,包括吸收系数、能带带隙、乌尔巴赫带尾参数、折射率等等.采用一套经验公式,描述InN薄膜在本征吸收区和乌尔巴赫吸收区的吸收系数.发现带隙以下,AlN薄膜的折射率遵守Sellmeier经验公式.用基于态密度和载流子—声子相互作用的带尾态理论,很好地解释了AlInN薄膜中带尾态现象.通过测量显微拉曼光谱,研究了AlInN薄膜的晶格振动性质.运用详细的模型(考虑了晶格热膨胀、残余应力和多声子耦合),阐释了AlInN声子频率的变温特性.了解AlInN薄膜的这些光学性质是相当重要的,不仅有利于透彻了解材料的基本性质还有利于相关光电子器件的开发.

Transmission and reflection measurements have been carried out on AlInN thin films.With the aid of a detailed procedure developed for analyzing the spectra,we obtained the effects of temperature on the optical properties of AlInN,such as the absorption coefficient,band-gap,Urbach bandtail characteristics,and refractive index.The absorption coefficient of the complete Urbach and intrinsic absorption regions of InN thin films has been described by a series of empirical formulas.The refractive index dispersion of AlN thin films below the band gap can be described by the Sellmeier equation.A bandtail model based on the calculation of density of occupied states and the carrier–phonon interaction has been employed to analyze the bandtail characteristics of AlInN thin films.We have also investigated Raman spectroscopy of AlInN thin films,with the emphasis on temperature dependence of phonon frequencies,which can be described well by a model taking into account the contributions of the thermal expansion of the crystal lattice,the strain between AlInN thin films and sapphire substrates,as well as three-and four-phonon coupling.These optical properties provide an experimental basis for further theoretical investigation and the design of AlInN-based devices.