GaN high-frequency device with self-aligned T-shaped gate and preparation method of GaN high-frequency device

The invention relates to a GaN high-frequency device with a self-aligned T-shaped gate and a preparation method thereof. The preparation method comprises the following steps: obtaining an epitaxial wafer; growing a first dielectric layer on the barrier layer; etching the first dielectric layer in a gate region until the upper surface of the barrier layer is exposed to form a gate window; growing a second dielectric layer in the gate window exposing the channel layer and on the barrier layer; etching the second dielectric layer in a partial region and the first dielectric layer right below the second dielectric layer, and exposing the barrier layer to form two active regions; performing ion implantation in the active region to form an ion implantation region, and then performing annealing treatment to form ohmic contact; growing a first dielectric layer on the barrier layer, the ion implantation region and the T-shaped second dielectric layer; removing the T-shaped second dielectric layer to prepare a T-shaped