Growth of undulating Si0.5Ge0.5 layers for photodetectors at λ = 1.55 μm

The Si0.5Ge0.5/Si multiquantum-well structures are grown using a production-compatible ultrahigh vacuum chemical vapor deposition system. The Si/SiGe/Si stack on a silicon-on-insulator wafer is used as the waveguiding layer. Transmission electron microscopy and photoluminescence are used to characterize the undulating layers. A photoluminescence emission corresponding to the band edge `no phonon' transition is measured at a wavelength beyond 1.55 μm. Preliminary data from metal-semiconductor-metal photodetectors fabricated with this material shoe a responsivity of approximately 0.1 A/W at the telecommunication wavelength of λ = 1.55 μm.