通过PECVD制备出了不同厚度的a-Ge∶H膜, 采用Raman光谱对样品进行了结构表征, 由椭圆偏振光谱仪得到样品的厚度和光学常数, 并计算了样品的光学带隙。由变温电导率分析了薄膜的电学输运性质, 结果表明, 载流子的传输机制为扩展态电导。进而利用变温PL谱研究了薄膜的发光性能, 发现其发光峰在1.63 μm处；随着膜厚的减小, 峰位和峰形都有改变, 且强度明显提高。进一步分析发现, 随着膜厚的减小非辐射复合跃迁的激活能增大, 从而导致辐射复合过程增强。

Ultra-thin hydrogenated amorphous germanium films, with various thickness from 160 nm to 5 nm were grown by plasma enhanced chemical vapor deposition technique. The film structure was characterized by Raman spectroscopy, which exhibited a broad band centered around 280 cm-1 indicating their amorphous nature. The film thickness and optical properties were evaluated by ellipsometer spectroscopy. The measured thickness was well consistent with the pre-designed value and the optical band gap was about 1 eV which slightly increased with the decrease of film thickness. The temperature dependent conductivity of the films was measured. The electronic transport was believed to occur in the extended-states and the corresponding activation energy is about 0.3～0.4 eV. The light emission in infrared region from the films can be detected at low temperature. The sample for 160 nm had a broad luminescence band which can be divided into two sub-bands centered at 0.78 eV and 0.67 eV, respectively. By decreasing the films thickness less than 10 nm, the luminescence band beaome narrower and only a band at 0.8 eV was observed. It may be due to the relatively more hydrogen in the ultrathin films, which passivated the defect states and suppressed the defect-related luminescence. The non-radiative activation energy increased in ultrathin films suggesting the improved efficiency.