Transistor including a stressed channel, a method for fabricating the same, and an electronic device including the same

A method for fabricating a semiconductor device, the method comprising:

• preparing a substrate which includes a first transistor region and a second transistor region;
• forming a first strained gate electrode which includes a first lattice-mismatched crystalline silicon layer disposed over the first transistor region;
• and
• forming a second strained gate electrode which includes a second lattice-mismatched crystalline silicon layer disposed over the second transistor region,
• wherein the forming of the first lattice-mismatched crystalline silicon layer comprises:
• forming an arsenic-doped crystalline silicon layer by doping only arsenic;
• and
• forming an undoped crystalline silicon layer disposed over the arsenic-doped crystalline silicon layer, the undoped crystalline silicon layer being undoped with arsenic, and
• wherein the forming of the second lattice-mismatched crystalline silicon layer comprises:
• forming a boron-doped crystalline silicon layer;
• and
• forming a germanium-doped crystalline silicon layer, the germanium-doped crystalline silicon layer being disposed over the boron-doped crystalline silicon layer.