GaN薄膜拉曼散射光谱的研究

利用拉曼散射光谱对在SiC衬底上采用MOCVD异质外延的未故意掺杂GaN薄膜特性进行研究发现E2模式向频率低的方向漂移表明在GaN薄膜中存在张力,由于SiC衬底不平整度增加引起更多位错的出现,从而引起拉曼谱中E2模式的加宽,因此通过选择平整度较好的衬底可以减小缺陷密度,提高薄膜的质量,此外A1(LO)模式的出现与强度可以用来表征未掺杂GaN的薄膜质量。

A study on Raman scattering spectra of GaN film

The properties of undopedGaN layers grown by MOCVD on SiC substrate were studied using Raman scattering spectra, The result indicate that there is tensile stress in GaN films since the E2 mode shifted to low frequency, with the roughness of SiC substrate being worse, much more dislocation is introduced and FWHM of E2 mode increased. Therefore the smooth substrate should be selected to decrease the defect density and improve the quality of the GaN , furthmore, whether A1(LO) mode existing or not and the intensity of A1(LO) can be used to identify the quality of GaN film.