We have used x-ray photoelectron spectroscopy (XPS) to measure the valence band offset in situ for coherently strained Si/Ge (100) heterojunctions grown by molecular beam epitaxy. Si 2p and Ge 3d core level to valence band edge binding energies and Si 2p to Ge 3d core level energy separations were measured as functions of strain, and strain configurations in all samples were determined using x-ray diffraction. We obtain valence band offsets of 0.83 :f: 0.11 eV and 0.22 0.13 eV for Ge coherently strained to Si (100) and Si coherently strained to Ge (100), respectively. If we assume that the offset between the weighted averages of the light-hole, heavy-hole, and spin-orbit valence bands in Si and Ge is independent of strain, we obtain a discontinuity in the average valence band edge of 0.49 0.13 eV.

Date Published: 1 October 1990
PDF: 8 pages
Proc. SPIE 1285, Growth of Semiconductor Structures and High-Tc Thin Films on Semiconductors, (1 October 1990); doi: 10.1117/12.20822

Published in SPIE Proceedings Vol. 1285:
Growth of Semiconductor Structures and High-Tc Thin Films on Semiconductors
Anupam Madhukar, Editor(s)