A semiconductor device includes a heat dissipation substrate and a device layer. The thermal conductivity of the heat dissipation substrate is greater than 200 Wm−1K−1 and the device layer is disposed on the heat dissipation substrate. The device layer includes a transistor. A method of forming a semiconductor device includes providing a base substrate, forming a heat dissipation substrate on the base substrate, wherein a thermal conductivity of the heat dissipation substrate is greater than 200 Wm−1K−1. The method further includes forming a device layer on the heat dissipation substrate, wherein the device layer comprises a transistor. The method further includes removing the base substrate.