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In this work, characterizations are conducted to investigate the threshold voltage (VTH) stability of the normally‐off GaN metal–insulator–semiconductor (MIS‐) field‐effect transistor (FET) with fully recessed gate structure and highly reliable low‐pressure chemical vapor deposition SiNx gate dielectric. We conducted bias‐temperature instability (BTI) tests under both positive and negative gate bias. We demonstrated the highly stable VTH of the high‐performance MIS‐FETs with small BTI, which benefits from the effective interfacial protection layer. More specifically, combining the BTI tests and drain current 1/f noise analysis, we present extensive investigation of the physical origins of BTI. According to the experimental evidence and analysis, we ascribe the VTH instability to the trapping/detrapping of the pre‐existing trap states located at the SiNx/GaN interface and/or in the gate dielectric. [ABSTRACT FROM AUTHOR]

Developing effective technique to protect the etched- GaN surface from the degradation in a high-temperature (i.e., at ~ 780°C) process, such as low-pressure chemical vapor deposition (LPCVD), is essential for fabricating normally-off GaN MIS-FETs with high-quality dielectric/GaN interface and highly reliable gate dielectric. In this letter, we developed an approach of obtaining such a protection layer using oxygen-plasma treatment followed by in situ annealing prior to the LPCVD-SiNx deposition. A sharp and stable crystalline oxidation interlayer (COIL) between the LPCVD-SiNx and etched-GaN was successfully formed. The LPCVD-SiNx/GaN MIS-FETs with COIL deliver normally-off operation with a VTH of 1.15 V, small on-resistance, small hysteresis, and thermally stable VTH . [ABSTRACT FROM AUTHOR]

In this letter, we demonstrate an integrated process that illustrates the compatibility of AlN/SiNx passivation with high-performance (i.e. low leakage and high breakdown) low-pressure chemical vapor deposition (LPCVD) SiNx gate dielectric for GaN-based MIS-HEMT. It is shown that the AlN/SiNx passivation structure maintains its superior capability of suppressing the current collapse after enduring high temperature of 780 °C during the LPCVD-SiNx deposition. The AlN/SiNx passivation is shown to be significantly better than the LPCVD-SiNx passivation by delivering small dynamic $R_{{\mathrm{\scriptscriptstyle ON}}}$ degradation, especially under high drain bias switching with $V_{{\mathrm{DS}}} > 100$ V. [ABSTRACT FROM PUBLISHER]

In this paper, we systematically investigated the leakage and breakdown mechanisms of the low-pressure chemical vapor deposition (LPCVD) silicon nitride thin film deposited on AlGaN/GaN heterostructures. The LPCVD-SiNx gate dielectric exhibits low leakage and high breakdown electric field. The dominant mechanism of the leakage current through LPCVD-SiNx gate dielectric is identified to be Poole–Frenkel emission at low electric field and Fowler–Nordheim tunneling at high electric field. Both electric-field-accelerated and temperature-accelerated time-dependent dielectric breakdown of the LPCVD-SiNx gate dielectric were also investigated. [ABSTRACT FROM PUBLISHER]

In this letter, silicon nitride (SiNx) film deposited at 780 °C by low-pressure chemical vapor deposition (LPCVD) was employed as gate dielectric for GaN-based metal–insulator–semiconductor high-electron-mobility transistors. The LPCVD-SiNx exhibit improved gate dielectric performance than the plasma enhanced chemical vapor deposition-SiNx, including smaller forward and reverse gate leakage, and higher forward gate breakdown voltage. [ABSTRACT FROM AUTHOR]