Growth of undulating Si_0.5Ge_0.5 layers for photodetectors at λ=1.55 μm

Si_0.5Ge_0.5/Si multiquantum-well structures are grown using a production-compatible ultrahigh vacuum chemical vapor deposition system. The structures are designed in order to obtain dislocation-free undulating strained layers used as the absorbing layers in photodetector structures. 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 show a responsivity of approximately 0.1 A/W at the telecommunication wavelength of λ=1.55 μm. © 1999 American Institute of Physics.