A semiconductor device may include a multi-layer gate dielectric layer and an electronic apparatus including the semiconductor device. The semiconductor device may include a channel layer including a two-dimensional semiconductor material, a gate dielectric layer on a first area of the channel layer, a gate electrode on the gate dielectric layer, and source and drain electrodes in a second area of the channel layer. The gate dielectric layer may include a high-k dielectric layer and an intermediate dielectric layer. The intermediate dielectric layer may be between the high-k dielectric layer and the channel layer. A dielectric constant of the intermediate dielectric layer may be less than a dielectric constant of the high-k dielectric layer.