MOLECULAR-BEAM EPITAXY OF SIGE HETEROSTRUCTURES USING A NEWLY DESIGNED SI EFFUSION CELL

We demonstrate the usefulness of a newly designed Si effusion cell whi ch can be used at high temperatures up to 1700 degrees C instead of a conventional electron beam evaporator in solid-source Si molecular bea m epitaxy. The growth rate ranges from 0.005 to 0.5 Angstrom s(-1) at temperatures from 1350 to 1650 degrees C and agrees well with the temp erature dependence of the Si vapor pressure. Photoluminescence was obs erved from a Si/SiGe quantum well grown on a Si substrate using the Si effusion cell. This indicates that the sample has little defects or d islocations which may result in nonradiative recombination centers or jeep levels. It is found from photoreflectance and X-ray diffraction m easurements that excellent controllability of the growth rate can be r ealized by using the Si effusion cell. (C) 1998 Elsevier Science S.A. All rights reserved.