Si基Ge光电探测器的研制及性能分析

Fabrication and Characteristics of Ge Photodiodes on Si Substrate

以Si衬底上外延Ge薄膜为吸收区,研究了Si基Ge光电探测器的材料生长与器件制作工艺,并对材料晶体质量和器件性能进行表征分析。Ge薄膜是采用低温缓冲层技术在超高真空化学气相沉积系统上生长的。1μm厚Ge薄膜的表面仅出现纳米量级的岛,表面粗糙度只有1.5 nm。Ge薄膜的X射线衍射峰形对称,峰值半高宽低于100 arc sec。Ge薄膜中存在0.14%的张应变。Si基Ge光电探测器在-1 V偏压时暗电流密度为13.7 mA/cm2,在波长1.31μm处的响应度高达0.38 A/W,对应外量子效率为36.0%,响应波长扩展到1.6μm以上。

Ge photodiodes on Si substrate operating in the near infrared region were demonstrated. The epitaxial Ge films were grown in an ultrahigh vacuum chemical vapor deposition system using low temperature Ge buffer technique. The 1 μ m thick Ge surface measured by atomic force microscopy exhibited some small islands with diameters at the nanoscale with a root-mean-square roughness of 1.5 nm. The X-ray diffraction peak of Ge fihn was symmetry and sharp, the full width at half maximum was less than 100 arc sec. The Ge film was tensilely trained, and the tensile strain was calculated to be 0.14%. The photodiode showed a dark current density of 13.7 mA/cm2 at -1 V reverse bias. A responsivity of 0.38 A/W at the wavelength of 1.31 μ m, corresponding to an external quantum efficiency of 36% was presented. The response wavelength was extended to above 1.6 μm.