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In this paper, we successfully demonstrate a recessed gate normally-off GaN FET on a silicon substrate with high threshold voltage (Vth) uniformity and low on-resistance. In order to realize high Vth uniformity, a novel Vth control technique is proposed, which we call Â¿piezo neutralization techniqueÂ¿. This technique includes a piezo neutralization (PNT) layer formed at the bottom of the gate recess. Since the PNT layer neutralizes the polarization charges under the gate, the Vth comes to be independent of the gate-to-channel span. The fabricated normally-off GaN FET with PNT structure exhibits an excellent Vth uniformity (Â¿(Vth) = 18 mV) and a state-of-the-art combination of the specific on-resistance (RonA = 500 m Â¿ mm2) and the breakdown voltage (VB > 1000 V). The normally-off GaN FETs wtih PNT structure show great promise as power devices.