S. Madhavi et al., High room-temperature hole mobility in Ge0.7Si0.3/Ge/Ge0.7Si0.3 modulation-doped heterostructures, J APPL PHYS, 89(4), 2001, pp. 2497-2499
Modulation-doped two-dimensional hole gas structures consisting of a strain
ed germanium channel on relaxed Ge0.7Si0.3 buffer layers were grown by mole
cular-beam epitaxy. Sample processing was optimized to substantially reduce
the contribution from the parasitic conducting layers. Very high hall mobi
lities of 1700 cm(2)/V s for holes were observed at 295 K which are the hig
hest reported to date for any kind of p-type silicon-based heterostructures
. Hall measurements were carried out from 13 to 300 K to determine the temp
erature dependence of the mobility and carrier concentration. The carrier c
oncentration at room temperature was 7.9 x 10(11) cm(-2) and decreased by o
nly 26% at 13 K, indicating very little parallel conduction. The high-tempe
rature mobility obeys a T-alpha behavior with alpha similar to 2, which can
be attributed to intraband optical phonon scattering. (C) 2001 American In
stitute of Physics.