A semiconductor device includes a compound semiconductor layer, where the compound semiconductor layer includes separate fin patterns in separate regions. The separate fin patterns may include different materials. The separate fin patterns may include different dimensions, including one or more of width and height of one or more portions of the fin patterns. The separate fin patterns may include an upper pattern and a lower pattern. The upper pattern and the lower pattern may include different materials. The upper pattern and the lower pattern may include different dimensions. Separate regions may include separate ones of an NMOS or a PMOS. The semiconductor device may include gate electrodes on the compound semiconductor layer. Separate gate electrodes may intersect the separate fin patterns.