A semiconductor device comprises a base substrate, a silicon oxide layer formed
on the base substrate, a first semiconductor layer formed on the silicon oxide
layer, the first semiconductor layer including an SiGe layer with a Ge concentration
not less than 30 atomic %, a second semiconductor layer formed on the first semiconductor
layer, the second semiconductor layer including a Ge layer or an SiGe layer with
a Ge concentration higher than the first semiconductor layer, a gate electrode
configured to induce a channel in a surface region of the second semiconductor
layer, and a gate insulating film formed between the second semiconductor layer
and the gate electrode.
