The invention relates to a comb-type gate structure HEMT
radio frequency device and a preparation method thereof. The comb-type gate structure HEMT
radio frequency device comprises an AlN buffer layer, an AlGaN buffer layer with a gradually-changed Al component, a GaN channel layer, an AlGaN layer, a source
electrode, a drain
electrode and a comb-type gate located between the source
electrode and the drain electrode; the comb-type gate comprises a gate head and a gate foot; the gate foot comprises a first sub-gate foot, a second sub-gate foot and a third sub-gate foot; the first sub-gate foot, the second sub-gate foot and the third sub-gate foot are sequentially arranged on the surface of the AlGaN layer at intervals in the direction from the source electrode to the drain electrode, and an air gap is formed between every two adjacent sub-gate feet. Due to the arrangement of the comb-type gate structure, the
gate resistance is reduced, the
noise coefficient is reduced, and meanwhile, the
gain is improved; a
passivation layer medium is not arranged between the gate head and the gate foot, and air is arranged in a gap between the adjacent gate feet, so that the
parasitic capacitance of the gate is reduced, and the
cut-off frequency is improved; and the three gate feet are arranged at intervals, so that the control of the gate to a channel is enhanced, the
transconductance is more stable along with the change of gate-source
voltage, and the
linearity is obviously improved.