Abstract: Provided is a semiconductor device. The semiconductor device includes a phase change material layer on a substrate, a gate electrode disposed on the phase change material layer and inducing accumulation of charges in the phase change material layer, and a pair of source/drain electrodes spaced apart from each other with the gate electrode therebetween on the phase change material layer. The phase change material layer includes a phase change region having a crystal structure that changes due to the accumulation of the charges as a voltage is applied to the gate electrode.