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.