High-Performance Normally-OFF GaN MIS-HEMTs Using Hybrid Ferroelectric Charge Trap Gate Stack (FEG-HEMT) for Power Device Applications

A GaN metal-insulator-semiconductor-high electron mobility transistor (HEMT) using hybrid ferroelectric charge trap gate stack (FEG-HEMT) is demonstrated for normally-OFF operation. The ferroelectric (FE) polarization increases the number of trapped charges in the HfON charge trapping layer, leading to high positive threshold voltage (V
_th
) shift for the normally-OFF device. Besides, under the positive bias temperature instability (PBTI) test, the internal electric field induced by FE polarization causes smoother slope of the conduction band in FE gate stack, resulting in better V
_th
stability. With the proposed hybrid FE charge trap gate stack, the device exhibits a high V
_th
of +2.71 V at I
_Dh
= 1μA/mm, a high maximum current density of 820 mA/mm and low on-resistance (R
_ON
) of 11.1 Ω · mm. The FE device also shows good V
_th
-temperature stability compared to the non-FE device results. Besides, a high current device with 40 A is also fabricated in this letter to demonstrate the feasibility of the proposed FEG-HEMT device for high power device application.