The temperature dependence of lateral conductivity and hole mobility in bor
on doped Si/SiGe/Si quantum well structures were studied. The conductivity
at the temperatures below 20 K is shown to be due to hopping over B centers
while at higher temperatures it is due to two-stage excitation consisting
of thermal activation of holes from the ground to strain-split B states and
the next hole tunneling into the valence band. (C) 1999 Academic Press.