利用AlGaN薄膜透射谱提取材料参数的研究

Extraction of Material Parameters by Transmission Spectra of AlGaN Film

为了研究多层结构高铝组分AlGaN薄膜材料的光学性能,并计算得到相关光学参数,本文基于多层膜传输矩阵方法,对两个样品的透射光谱进行了拟合。根据AlGaN材料对不同波长入射光的吸收机制,并考虑了材料在带外的弱吸收,建立了全波段(200~800 nm)范围内的吸收系数模型,同时引入表面粗糙度均方根参数来表征材料表面粗糙度对透射谱的影响。采用所建模型对结构参数不同的两个Al0.65Ga0.35N样品的透射谱进行拟合,拟合结果与实验结果的一致性较好。本文得到的全波段范围内Al0.65Ga0.35N材料的吸收系数,为研究日盲紫外探测器的响应光谱提供了可靠的实验数据。同时,本文还得到了Al0.65Ga0.35N的膜层厚度、折射率、表面粗糙度等参数。

To study the optical properties of multilayer AlGaN films with high Al content and calculate the relevant optical parameters, we fitted the transmission spectra of two samples based on the method of the multilayer-film transfer matrix. According to the mechanism of the AlGaN materials absorbing the incident light on different wavelengths, considering the out-of-band weak absorption of the materials, we established an absorption coefficient model in the all-band range(200--800 nm). At the same time, the root mean square(RMS) parameter of surface roughness was introduced to characterize the effect of the surface roughness of the materials on the transmission spectra. Furthermore, the transmission spectra of two Al0.65Ga0.35N samples with different structural parameters were fitted by the proposed model, and the fitting results were in good agreement with the experimental results. The absorption coefficient of Al0.65Ga0.35N material in the all-band range provided reliable experimental data for the study of the response spectra of solar-blind UV detectors. Additionally, the parameters such as film thickness, refractive index, and surface roughness of the Al0.65Ga0.35N materials were also obtained.