Embodiments of this application provide a semiconductor device, an electronic device, and a semiconductor device preparation method, and relate to the field of chip manufacturing and packaging technologies, to improve heat dissipation efficiency of the semiconductor device without increasing a size. The semiconductor device includes: a substrate, a source, a drain, a gate, and a groove. The source, the drain, and the gate are all formed on the substrate, and an active region is formed between the source and the drain on the substrate. The groove is disposed in the substrate, and a spacing is formed between the groove and the active region. A heat dissipation layer is formed in the groove, and a coefficient of thermal conductivity of the heat dissipation layer is greater than that of the substrate.