Er/O doped Si1-xGex alloy layers grown by MBE

Silicon-based light emitting diodes (LEDs) containing an Er/O-doped Si1-chi Gechi active layer have been studied. The structures were grown by molecula r beam epitaxy (MBE), with Er and O concentrations of 5 x 10(19) and 1 x 10 (20) cm(-3) respectively, using Er and silicon monoxide sources. The micros tructure has been studied by X-ray diffraction (XRD) and cross-sectional tr ansmission electron microscopy, and it is found that Er/O-doped Si0.92Ge0.0 8 layers of high crystalline quality, can be obtained. Electroluminescence (EL) measurements have been performed on reverse-biased Er/O doped diodes b oth from the surface and from the edge and the emission at 1.54 mum associa ted with the Er3+ ions has been studied at 300 K and lower temperatures. To evaluate the possibility to use a Si1-chiGechi layer for waveguiding in Si -based optoelectronics, studies of the refractive index n of strained Si1-c hiGechi as a function of the Ge concentration have been done by spectroscop ic ellipsometry in the range 0.3-1.7 Gun. At 1.54 mum the refractive index increases monotonically with the Ge concentration up to n = 3.542 for a Ge concentration of 21.3%. (C) 2001 Elsevier Science B.V. All rights reserved.