A semiconductor device includes a channel layer located on a substrate, the channel layer including a conductive oxide, a gate structure located on the channel layer, the gate structure including a gate electrode and gate spacers located on both sidewalls of the gate electrode, and source and drain regions located on both sides of the gate structure in recess regions having a first height from a top surface of the channel layer. The source and drain regions are configured to apply tensile stress to a portion of the channel layer located under the gate structure.