Si/Si 1-x Ge x /Si low-loss waveguides fabricated using selective epitaxial growth

Abstract

ABSTRACT The realisation of two-dimensional Si/Si1Ge/Si strained layer low-loss waveguides (1.7 dB/cm at 1.3im) is reported. Thewaveguide structure is grown using selective epitaxy. This fabrication method insures loosened cut-off and critical thickness conditions as demonstrated previously by the room-temperature operation of vertical emitting SiGe/Si LED. The maindifference from other fabrication methods is the local deposition of the SiGe in a finite stripe region while in the conventional fabrication of rib waveguides the SiGe layer is deposited on an entire wafer and then patterned by reactive ion etching. The relative high amount of Ge (19%) incorporated in selectively grown waveguides, and reduced thickness (O.6im) of Si cap layer are improvements from the previous reported SiGe/Si waveguides where thick Si cap layers (fewmicrons) and reduced Ge concentrations (<10%) are necessary in order to obtain waveguiding.Keywords: SiGe/Si waveguides, selective epitaxy, waveguide photodetectors, photonic integrated circuits