High quality Ge was epitaxially grown on Si using ultrahigh vacuum/chemical vapor deposition (UHV/CVD). This paper demonstrates effcient germanium-on-silicon p-i-n photodetectors with 0.8 μm Ge, with responsivities as high as 0.38 and 0.21 A/W at 1.31 and 1.55 μm, respectively. The dark current density is 0.37 mA/cm2 and 29.4 mA/cm2 at 0 V and a reverse bias of 0.5 V.The detector with a diameter of 30 μm, a 3 dB-bandwidth of 4.72 GHz at an incident wavelength of 1550 nm and zero external bias has been measured. At a reverse bias of 3 V, the bandwidth is 6.28 GHz.
The Si epitaxial films are grown on Si (100) substrates using pure Si 2 H 6 as a gas source using ultrahigh vacuum chemical vapour deposition technology.The values of growth temperature T g are 650℃,700℃,730℃,750℃,and 800℃.Growth mode changes from island mode to step-flow mode with T g increasing from 650℃ to 700℃.Rippled surface morphologies are observed at T g=700℃,730℃,and 800℃,but disappear when T g=750℃.A model is presented to explain the formation and the disappearance of the ripples by considering the stability of the step-flow growth.
