A transistor device, such as a rotated channel metal oxide/insulator field effect transistor (RC-MO(I)SFET), includes a substrate including a non-polar or semi-polar wide band gap substrate material such as an Al2O3 or a ZnO or a Group-III Nitride-based material, and a first structure disposed on a first side of the substrate comprising of AlInGaN-based and/or ZnMgO based semiconducting materials. The first structure further includes an intentional current-conducting sidewall channel or facet whereupon additional semiconductor layers, dielectric layers and electrode layers are disposed and upon which the field effect of the dielectric and electrode layers occurs thus allowing for a high density monolithic integration of a multiplicity of discrete devices on a common substrate thereby enabling a higher power density than in conventional lateral power MOSFET devices.