High-performance waveguide-integrated Ge/Si avalanche photodetector with small contact angle between selectively epitaxial growth Ge and Si layers

Du Xiao-Qian^{1, 2}, Li Chong³, Li Ben³, Wang Nan^{1, 2}, Zhao Yue^{1, 2}, Yang Fan^{1, 2}, Yu Kai^{1, 2}, Zhou Lin^{1, 2}, Li Xiu-Li^{1, 2}, Cheng Bu-Wen^{1, 2}, Xue Chun-Lai^{1, 2, †}

(a) The dark current and photocurrent characteristics versus voltage of the 3.0- μ m -length and 1.5- μ m -length step-coupler Ge/Si APDs with 20- μ m -Ge-length. (b) The M scattergram of four types of devices.