The effect of carbon on the valence band offset of compressively strained Si1-x-yGexCy/(100) Si heterojunctions

Capacitance-voltage measurements have been used to study the effect of carbon on the valence band offset of compressively strained Si1-x-yGexCy/(100) Si heterojunctions grown by rapid thermal chemical vapor deposition with substitutional C levels from 0% to 2.5%. The valence band offset between Si1-x-yGexCy and unstrained (100) Si decreases at a rate of 20-26 meV per % C. Our work indicates that the change in the bandgap of Si1-x-yGexCy as carbon is added is entirely accommmodated in the valence band. (C) 1997 American Institute of Physics.