Unit cells of metal oxide semiconductor (MOS) transistors are provided including an integrated circuit substrate and a MOS transistor on the integrated circuit substrate. The MOS transistor has a source region, a drain region and a gate region, the gate region being between the source region and the drain region. First and second channel regions are provided between the source and drain regions. The channel region is defined by first and second spaced apart protrusions in the integrated circuit substrate separated by a trench region. The first and second protrusions extend away from the integrated circuit substrate and upper surfaces of the first and second protrusions are substantially planar with upper surfaces of the source and drain regions. A gate electrode is provided in the trench region extending on sidewalls of the first and second spaced apart protrusions and on at least a portion of surfaces of the first and second spaced apart protrusions.