Si基Ge波导共振腔增强型光电探测器的制备和特性研究

Fabrication and characteristics of Si-based resonant-cavity-enhanced waveguide photodetectors

采用低温缓冲层技术,在硅（Si）衬底上生长了质量 优良的锗（Ge）薄膜。Ge层受到由于Si和Ge热膨胀系数不同引入张应变,大小约为0. 16%。以 外延的Ge层作为吸收区,前后以Ge/空气作为分布布拉格反射镜（DBR）,在Si基上制备波导共 振腔增强 型（RCE）光电探测器。测试表明,器件在－1V偏压下,暗电流密度为14.9mA/cm2；在零偏压下, 器件的响应光谱在1.3～1.6μm波长范围内观察到4个共振增强峰,分别位于1.35、1.45、1.50和1.55μm,光响应波长范围扩展到1.6μm以上,采用传输矩阵法模拟的 响应光谱与实验测得结果近似吻合；在1.55μm入射光的照射下,测 得光响应度为21.4mA/W。

The epitaxial Ge layer was prepared in an ultrahigh vacuum chemical vapor deposition system using low tempe rature Ge buffer technique.The tensile strain of about 0.16% was induced by the thermal e xpansion coefficient mismatching between Si and Ge during the cooling process from elevat ed growth temperature.A Ge resonant-cavity-enhanced waveguide photodetector based on Si substrate was fabricated and characterized.The results show that the dark current density o f the device is 14.9mA/cm at the bias of -1V.The spectral response under zero bias shows four resonant peaks located at approximately 1.35μm,1.45μm,1.50μm and 1.55μm,respectively in the wavelength range from 1.3μm to 1.6μm,and the photocurrent spectrum in the wavelength ran ge is expanded to 1.6μm at 0V.The simulated response spectrum utilizing scattering matrix meth od approximately matches the measured data.A responsivity of 21.4mA/W at the wavelength of 1.55μm is presented.