We investigated electron transport in strained Si1-yCy alloy layers grown o
n Si(100) substrates using the Monte Carlo simulation. The electron mobilit
y higher than that of bulk Si over a wide range of temperatures from 40 K t
o 300 K is mainly attributed to the valley splitting induced by the tensile
strain in the Si1-yCy layer. For lower temperatures less than 100 K the mo
bility increases sharply depending on the carbon fraction up to about 0.6 %
. Beyond the fraction, however, it keeps almost constant regardless of incr
easing the carbon fraction. On the other hand, we observe a monotonic mobil
ity increase with increasing the carbon fraction for a higher temperature r
egime.