Abstract
A high electron mobility transistor (HEMT) device using a gate protection layer is provided. A substrate has a channel layer arranged on the substrate, and has a barrier layer arranged on the channel layer. The channel layer and the barrier layer define a heterojunction, and a gate structure is arranged on a gate region of the barrier layer. The gate structure includes a gate arranged on a cap, wherein the cap is disposed on the barrier layer. The gate protection layer is arranged along sidewalls of the cap, and arranged under the gate between the opposing surfaces of the gate and the cap. Advantageously, the gate protection layer passivates the gate, reduces leakage current along sidewalls of the cap, and improves device reliability and threshold voltage uniformity. A method for manufacturing the HEMT device is also provided.