Growth of undulating Si0.5Ge0.5 layers for photodetectors at lambda=1.55 mu m

Si0.5Ge0.5/Si multiquantum-well structures are grown using a production-com patible ultrahigh vacuum chemical vapor deposition system. The structures a re designed in order to obtain dislocation-free undulating strained layers used as the absorbing layers in photodetector structures. The Si/SiGe/Si st ack on a silicon-on-insulator wafer is used as the waveguiding layer. Trans mission electron microscopy and photoluminescence are used to characterize the undulating layers. A photoluminescence emission corresponding to the ba nd edge "no phonon'' transition is measured at a wavelength beyond 1.55 mu m. Preliminary data from metal-semiconductor-metal photodetectors fabricate d with this material show a responsivity of approximately 0.1 A/W at the te lecommunication wavelength of lambda = 1.55 mm. (C) 1999 American Institute of Physics. [S0021-8979(99)10215-9].