Power device and preparation method thereof

The embodiment of the invention provides a power device and a preparation method of the power device, and relates to the technical field of semiconductors, the power device comprises a compound semiconductor composite layer, a p-type gate layer, a source electrode, a drain electrode and a gate electrode layer, and the p-type gate layer, the source electrode and the drain electrode are all arranged on the compound semiconductor composite layer; the gate electrode layer is arranged on the p-type gate layer; wherein the side wall, close to one side of the drain electrode, of the p-type gate layer comprises a p-type gate slope, and the p-type gate slope is obliquely arranged towards the source electrode relative to the surface of the compound semiconductor composite layer. Compared with the prior art, electric field distribution at the corner of the grid electrode can be optimized, the withstand voltage of the device is improved, the field plate structure near the grid electrode is optimized, and the performance