A Si-based Ge waveguide photodetector was fabricated and characterized.High-quality tensile strained Ge layer(about 500nm)was epitaxially grown on a Si(100)substrate by low-and high-temperature two-step growth method in ultrahigh vacuum chemical vapor deposition.Two metal-germanium schottky junctions on and under the waveguide were fabricated to form metal-germanium-metal photodetector and the dark current density of 0.2 mA/cm2 at the bias of-1 V is obtained.The photocurrent response in the wavelength range...