This work adopts interface charge engineering to fabricate normally off metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) on an in situ SiNx/AlGaN/GaN platform using an in situ O3 treatment performed in the atomic layer deposition system. The combination of in situ SiNx passivation and an O3-treated Al2O3/AlGaN gate interface allows the device to provide an excellent breakdown voltage of 1498 V at a low specific on-resistance of 2.02 mΩ cm2. The threshold voltage is increased by 2 V by significantly compensating the net polarization charges by more than five times with O3 treatment as well as reducing the interface traps and improving the high-temperature gate stability. Furthermore, a physical model of fixed charges at the Al2O3/AlGaN interface is established based on dielectric thickness-dependent linear fitting and numerical calculations. The matched device performance and simulated energy band bending elucidate the O3-treated fixed-charge modulation mechanism, providing a practical method for producing normally off GaN MIS-HEMTs.

In this work, a dramatic reduction in current collapse is achieved in GaN-based high-electron-mobility transistors (HEMTs) using dual-layer SiNx stressor passivation (DSSP), and the related mechanism is proposed. The SiNx compression neutralizes the inherent piezo polarization caused by the lattice mismatch at the heterojunction and effectively mitigates the peak electric field crowding at the drain-side gate edge, as supported by technology computer-aided design simulation. Thus, the inverse piezoelectric effect is suppressed and the trapped charge density is reduced under high electrical stress. As a result, the current collapse effect can be significantly restrained. Upon pulsing (Vg = −6 and Vds = 20 V), the device with DSSP exhibits a negligible current collapse (∼3%), which is significantly lower than the baseline device (∼34%). Moreover, it shows a one-order-of-magnitude reduction in gate leakage and a significant enhancement in gate stability. These results prove that the DSSP process is an attractive technique to facilitate high-reliability GaN-on-Si HEMTs.

In this work, we present the novel application of SiN_x stress-engineering techniques for the suppression of short-channel effects in AlGaN/GaN high-electron-mobility transistors (HEMTs), accompanied by a comprehensive analysis of the underlying mechanisms. The compressive stress SiN_x passivation significantly enhances the barrier height at the heterojunction beneath the gate, maintaining it above the quasi-Fermi level even as V_ds rises to 20 V. As a result, in GaN devices with a gate length of 160 nm, the devices with compressive stress SiN_x passivation exhibit significantly lower drain-induced barrier lowering (DIBL) factors of 2.25 mV/V, 2.56 mV/V, 4.71 mV/V, and 3.84 mV/V corresponding to drain bias voltages of 5 V, 10 V, 15 V, and 20 V, respectively. Furthermore, as V_ds increases, there is an insignificant degradation in transconductance, subthreshold swing, leakage current, or output conductance. In contrast, the devices with stress-free passivation show relatively higher DIBL factors (greater than 20 mV/V) and substantial degradation in pinch-off performance and output characteristics. These results demonstrate that the SiN_x stress-engineering technique is an attractive technique to facilitate high-performance and high-reliability GaN-based HEMTs for radio frequency (RF) electronics applications.

In this work, high threshold voltage and breakdown voltage E-mode GaN HEMTs using an Al:HfOx-based charge trapping layer (CTL) are presented. The developed GaN HEMTs exhibit a wide threshold modulation range of ΔVTH ∼ 17.8 V, which enables the achievement of enhancement-mode (E-mode) operation after initialization process owing to the high charge storage capacity of the Al:HfOx layer. The E-mode GaN HEMTs exhibit a high positive VTH of 8.4 V, a high IDS,max of 466 mA/mm, a low RON of 10.49 Ω mm, and a high on/off ratio of ∼109. Moreover, the off-state breakdown voltage reaches up to 1100 V, which is primarily attributed to in situ O3 pretreatment effectively suppressing and blocking leakage current. Furthermore, thanks to the VTH of GaN HEMTs being tunable by initialization voltage using the proposed CTL scheme, we prove that the direct-coupled FET logic-integrated GaN inverters can operate under a variety of conditions (β = 10–40 and VDD = 3–15 V) with commendable output swing and noise margins. These results present a promising approach toward realizing the monolithic integration of GaN devices for power IC applications.

This study optimizes the CuO_x/Ga₂O₃ heterojunction diodes (HJDs) by tailoring the structural parameters of CuO_x layers. The hole concentration in the sputtered CuO_x was precisely controlled by adjusting the Ar/O₂ gas ratio. Experimental investigations and TCAD simulations were employed to systematically evaluate the impact of the CuO_x layer dimension and hole concentration on the electrical performance of HJDs. The results indicate that increasing the diameter dimension of the CuO_x layer or tuning the hole concentration to optimal values significantly enhances the breakdown voltage (V_B) of single-layer HJDs by mitigating the electric field crowing effects. Additionally, a double-layer CuO_x structure (p⁺ CuO_x/p⁻ CuO_x) was designed and optimized to achieve an ideal balance between the V_B and specific on-resistance (R_on,sp). This double-layer HJD demonstrated a high V_B of 2780 V and a low R_on,sp of 6.46 mΩ·cm², further yielding a power figure of merit of 1.2 GW/cm². These findings present a promising strategy for advancing the performance of Ga₂O₃ devices in power electronics applications.

This study presents a β-Ga2O3 Schottky barrier diode (SBD) with a Mg current blocking layer (Mg-CBL) fabricated via the Mg-doped spin-on-glass (Mg-SOG) technique, affording a surface roughness damage-free thermal doping process. The proposed technique improves the breakdown voltage (BV) of the β-Ga2O3 SBD from 580 to 2200 V and marginally increases the specific on-resistance from 4.0 to 4.8 mΩ cm2, yielding a notable power figure of merit exceeding 1 GW/cm2. The Mg-CBL effectively captures the electrons and mitigates the electric field, leading to a significant increase in BV and slight decrease in the forward current loss. The temperature-dependent I–V curves reveal that the reverse saturation current decreases owing to the physical mechanism of the Mg-CBL structure. Moreover, the Gaussian distribution model is applied to correct the Schottky barrier inhomogeneity stemming from the Mg-CBL. The results illustrate the promising potential of the Mg-CBL fabricated via the Mg-SOG technique for yielding high-performance β-Ga2O3 SBDs.