Author Affiliations
Abstract
1 Laboratory of Thin Film Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
3 Key Laboratory of Materials for High Power Laser, Chinese Academy of Sciences, Shanghai 201800, China
4 Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
Ultrathin Ge films with thickness of about 15 nm at different deposition temperatures were prepared by electron beam evaporation. Spectral measurement results showed that as the deposition temperature increased from 100°C to 300°C, the transmittance of the films in the wavelength range from 350 nm to 2100 nm decreased. After annealing in air at 500°C, the transmittance significantly increased and approached that of uncoated fused quartz. Based on the Tauc plot method and Mott–Davis–Paracrystalline model, the optical band gap of Ge films was calculated and interpreted. The difference in optical band gap reveals that the deposition temperature has an effect on the optical band gap before annealing, while having little effect on the optical band gap after annealing. Furthermore, due to oxidation of Ge films, the optical band gap was significantly increased to ～5.7 eV after annealing.
Ge films transmittance optical band gap deposition temperature annealing Chinese Optics Letters
2020, 18(10): 103101
南京大学物理学系 江苏省光电信息功能材料重点实验室, 江苏 南京 210093
用化学气相淀积方法, 在Si (100) 衬底上生长Si1-xGex∶C合金作为缓冲层、继而外延生长了Ge晶体薄膜, 用X射线衍射(XRD)、俄歇电子能谱(AES)、拉曼(Raman)衍射光谱等对所得到的样品进行了表征测量, 着重研究了Si1-xGex∶C缓冲层生长温度对样品结构特征的影响。结果表明：Si1-xGex∶C缓冲层中的Ge原子浓度沿表面至衬底方向逐渐降低, 其平均组分随着生长温度的升高而降低, 这与较高生长温度(760～820℃)所导致的原子扩散效应相关; 在Si1-xGex∶C缓冲层上外延生长的Ge薄膜具有单一的晶体取向,薄膜的晶体质量随着温度的升高而降低。
Ge薄膜 Si1-xGex∶C缓冲层 化学气相淀积 生长温度
