The invention discloses a
semiconductor device and a preparation method thereof. The
semiconductor device sequentially comprises a substrate; a multilayer
semiconductor layer and a P-type epitaxial layer; an
anode which is positioned on one side, far away from the multilayer semiconductor layer, of the P-type epitaxial layer; and a
cathode which is positioned on one side, far away from the substrate, of the multilayer semiconductor layer, wherein the
vertical projection of the
anode on the substrate is at least partially overlapped with the
vertical projection of the P-type epitaxial layer onthe substrate. By adopting the technical scheme, the P-type epitaxial layer is additionally arranged in the
semiconductor device, and the two-dimensional
electron gas below the
anode is exhausted by lifting the energy band through the P-type epitaxial layer, so that the device electric leakage of the
semiconductor device is reduced; on the other hand, the
semiconductor device does not need to etchmultiple semiconductor
layers to form an anode groove,
etching damage does not exist, and the interface state of a traditional anode groove structure is avoided; compared with an anode groove etchingprocess, the uniformity of the P-type epitaxial layer is better, and the consistency of forward turn-on
voltage of the device can be improved.