A semiconductor device is provided. The semiconductor device includes a plurality of first epitaxial layers, a second epitaxial layer and a gate structure. The plurality of first epitaxial layers is stacked on a substrate and has a first conductivity type. Each first epitaxial layer includes at least one first doping region and at least one second doping region adjacent thereto. The first doping region has a second conductivity and the second doping region has the first conductivity type. The second epitaxial layer is disposed on the plurality of first epitaxial layers, having the first conductivity type. The second epitaxial layer has a trench therein and a third doping region having the second conductivity type is adjacent to a sidewall of the trench. The gate structure is disposed on the second epitaxial layer above the second doping region. A method of fabricating a semiconductor device is also disclosed.