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The effects of the parasitic gate capacitance and gate resistance (Rg) on the radiofrequency (RF) performance are investigated in LG = 0.15 μm GaN high‐electron‐mobility transistors with T‐gate head size ranging from 0.83 to 1.08 μm. When the device characteristics are compared, the difference in DC characteristics is negligible. The RF performance in terms of the current‐gain cut‐off frequency (fT) and maximum oscillation frequency (fmax) substantially depend on the T‐gate head size. For clarifying the T‐gate head size dependence, small‐signal modeling is conducted to extract the parasitic gate capacitance and Rg. When the T‐gate head size is reduced from 1.08 to 0.83 μm, Rg increases by 82%, while fT and fmax improve by 27% and 26%, respectively, because the parasitic gate–source and gate–drain capacitances reduce by 19% and 43%, respectively. Therefore, minimizing the parasitic gate capacitance is more effective that reducing Rg in our transistor design and fabrication, leading to improved RF performance when reducing the T‐gate head size. [ABSTRACT FROM AUTHOR]

The effects of the parasitic gate capacitance and gate resistance (Rg) on the radiofrequency (RF) performance are investigated in LG = 0.15 μm GaN high-electron-mobility transistors with T-gate head size ranging from 0.83 to 1.08 μm. When the device characteristics are compared, the difference in DC characteristics is negligible. The RF performance in terms of the current-gain cut-off frequency (fT) and maximum oscillation frequency (fmax) sub-stantially depend on the T-gate head size. For clarifying the T-gate head size dependence, small-signal modeling is conducted to extract the parasitic gate capacitance and Rg. When the T-gate head size is reduced from 1.08 to 0.83 μm, Rg increases by 82%, while fT and fmax improve by 27% and 26%, respectively, because the parasitic gate–source and gate–drain capacitances reduce by 19% and 43%, respectively. Therefore, minimizing the parasitic gate capacitance is more effective that reducing Rg in our transistor design and fabrication, leading to improved RF performance when reducing the T-gate head size.

In this paper, we report DC and RF analysis of a T‐gate AlN/β‐Ga2O3 high electron mobility transistors (HEMTs) by optimizing the gate‐drain distance (LGD) and two T‐gate dimensions given by the—head‐length (LHL) and the foot‐length (LFL). A two‐dimensional (2‐D) physics‐based device simulator attuned with experimental results is used to perform the analysis. The AlN/β‐Ga2O3 HEMT achieves a high two‐dimensional electron gas (2DEG) density of ~3 × 1013 cm−2, which is attributed to large spontaneous as well as piezoelectric polarization components of the 10 nm AlN thick barrier layer. 2DEG density is also numerically validated using widely used polarization model for III nitrides. It is demonstrated that a highly scaled, both lateral and vertical, device with optimized T‐gate dimensions achieves higher blocking voltage (VBR), low on‐resistance (RON), higher cut‐off frequency (fT) and higher maximum oscillation frequency (fMAX), simultaneously. Consequently, AlN/β‐Ga2O3 HEMT achieves a low specific‐on resistance (RON,sp) of 0.1 mΩ cm2 and an off‐state breakdown voltage of 904 V, which corresponds to the record power figure‐of‐merit (PFoM) of ~8172 MW/cm2. Furthermore, fT of 73 GHz and fMAX of 142 GHz are estimated. These results—low power conduction loss along with higher blocking voltage, and superior RF parameters show the potential of the analyzed device T‐gate AlN/β‐Ga2O3 HEMT for high‐power switching and RF applications. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive investigation into the DC analog and AC microwave performance of a state-of-the-art T-gate double barrier AlGaN/AlInGaN/GaN MOSHEMT (Metal Oxide Semiconductor High Electron Mobility Transistor) implemented on a 4H-SiC substrate. The study involves meticulous numerical simulations and an extensive comparison with a single barrier design, utilizing the TCAD-Silvaco software. The observed disparity in performance can be attributed to the utilization of double barrier technology, which enhances electron confinement and current density by augmenting the polarization-induced charge during high-frequency operations. Remarkably, when compared to the single barrier design, the double barrier MOSHEMT exhibits a notable 15% increase in drain current, a 5% increase in transconductance, and an elevated breakdown voltage (VBR) of 140 V in E-mode operation. Furthermore, the radio frequency analysis of the double barrier device showcases exceptional performance, setting new records with a maximum oscillation frequency (fmax) of 1.148 THz and a gain cutoff frequency (ft) of 891 GHz. These impressive results obtained through deck-simulation affirm the immense potential of the proposed double barrier AlGaN/AlInGaN/GaN MOSHEMT for future applications in high-power and terahertz frequency domains.

The influence of double deck T-gate on LG = 0.2 μm AlN/GaN/AlGaN HEMT is analysed in this paper. The T-gate supported with Silicon Nitride provides a tremendous mechanical reliability. It drops off the crest electric-field at gate edges and postponing the breakdown voltage of a device. A 0.2-μm double deck T-gate HEMT on Silicon Carbide substrate offer fMAX of 107 Giga Hertz, fT of 60 Giga Hertz and the breakdown voltage of 136 Volts. Furthermore, it produces the maximum-transconductance and drain-current of 0.187 Siemens/mm and 0.41 Ampere/mm respectively. In addition, the lateral electric-field noticed at gate-edge shows 2.1 × 106 Volts/cm. Besides, the double deck T-gate AlN/GaN HEMT achieves a 45% increment in breakdown voltage compared to traditional GaN-HEMT device. Moreover, it reveals a remarkable Johnson figure-of-merit of 7.9 Tera Hertz Volt. Therefore, the double deck T-gate on AlN/GaN/AlGaN HEMT is the superlative device for 60 GHz V-band satellite application. [ABSTRACT FROM AUTHOR]

A new e-beam lithography method using stepping exposure was proposed to obtain a floating Y-gate for high electron mobility transistor (HEMT) application. The resist thickness shows good linearity with the exposure dose. An AlGaN/GaN HEMT device with 120 nm gate length was fabricated by this method. The device shows improved breakdown and frequency performance (fmax∙BV increased by 55%) compared to the traditional T-gate device. [Display omitted] • The stepping litho method shows a good linearity with exposure dose. • The Y-gate shows about 23° of dip angle. • The Y-gate improves the f t /f max and the BV of device at the same time. • The f max ∙BV of Y-gate device is improved 55% compared with T-gate device. [ABSTRACT FROM AUTHOR]