| Abstract | Design and development of basic optical components are vital for the future development of all optical and optoelectronic circuits. Optical components fabricated on Si are restricted to operation at wavelengths below 1.1 micrometers . However, the incorporation of SiGe in Si devices enables operation to be extended to the communications wavelengths of 1.3 micrometers and 1.5 micrometers . Optical modulation in a Si/Si0.85Ge0.15/Si, MBE grown, waveguide p-i-n diode was experimentally investigated at a wavelength of 1.3 micrometers . When the waveguide p-i-n diode is forward biased, the injected free carriers absorb the light propagating in the intrinsic layer thereby giving a strong modulation of the device output intensity. The modulator, grown on a 2 X 1019 cm-3 n++-Si substrate, consists of a 2.5 micrometers thick, 7 X 1015 cm-3 n-Si layer, a 0.1 micrometers thick i-Si0.85Ge0.15 guiding layer, a 2 mumm thick, 2.5 X 1016 cm-3 p-Si layer and a 0.1 micrometers thick, 2 X 1020 cm-3 p++)-Si contact layer. Under forward bias the p-i-n diode achieves a carrier density of 5 X 1018 cm-3 in the guiding layer of the waveguide. A maximum modulation depth of 66% was obtained for a 2 mm long, 37.5 micrometers wide ridge waveguide at a peak pulse current density of 2700 A/cm2. |
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