HEMT device and preparation method thereof

The invention provides an HEMT device and a preparation method thereof. The HEMT device comprises a substrate, a channel layer, a barrier layer, a P-type GaN grid electrode, a grid electrode, a source electrode and a drain electrode. The channel layer is located on the substrate, the barrier layer is located on the channel layer, and two-dimensional electron gas is formed at the interface of the barrier layer and the channel layer; the P-type GaN grid electrode, the source electrode and the drain electrode are distributed on the barrier layer at intervals, the grid electrode is located above the P-type GaN grid electrode, the source electrode and the drain electrode are located on the two opposite sides of the P-type GaN grid electrode, a passivation region is formed in the HEMT device, and the P-type GaN grid electrode is located above the passivation region. The passivation region extends into the barrier layer between the grid electrode and the drain electrode from the lower part of the P-type GaN grid ele