Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistor and Its RF Power Efficiency Optimization with Source-Bridged Field-Plate Structure

Abstract

In this study, we consider the relationship between the temperature in a two-dimensional electron gas (2-DEG) channel layer and the RF characteristics of an AlGaN/GaN high-electron-mobility transistor by changing the geometrical structure of the field-plate. The final goal is to achieve a high power efficiency by decreasing the channel layer temperature. First, simulations were performed to compare and contrast the experimental data of a conventional T-gate head structure. Then, a source-bridged field-plate (SBFP) structure was used to obtain the lower junction temperature in the 2-DEG channel layer. The peak electric field intensity was reduced, and a decrease in channel temperature resulted in an increase in electron mobility. Furthermore, the gate-to-source capacitance was increased by the SBFP structure. However, under the large current flow condition, the SBFP structure had a lower maximum temperature than the basic T-gate head structure, which improved the device electron mobility. Eventually, an optimum position of the SBFP was used, which led to higher frequency responses and improved the breakdown voltages. Hence, the optimized SBFP structure can be a promising candidate for high-power RF devices.

Operational Improvement of AlGaN/GaN High Electron Mobility Transistor by an Inner Field-Plate Structure

“…Premature impact ionization results in a soft breakdown in the source-side FP structure [29], whereas the drain-side FP undergoes a hard breakdown, owing to a delayed impact ionization following the avalanche process. In FP technology, there is a direct dependence of breakdown voltage on the correlation between the carrier density and the electric field [30,31]. Therefore, T-shaped gate FP structures are exploited to account for both source-side and drain-side electric fields and, hence, carrier concentrations.…”

Influence of AlN passivation on thermal performance of AlGaN/GaN high-electron mobility transistors on sapphire substrate: A simulation study

“…The SHEs have hindered the manufacturing of high-quality HEMTs that become dominant when drain bias is applied, leading to sub-optimal breakdowns. Extensive researches have been conducted to overcome the SHEs by various research groups using advanced field plate structures, excessive thermal stability material, and air-water cooling device framework [15][16][17][18][19]. However, even after lots of research, an optimized device has not been proposed to meet the market power-requirements.…”

Effects of notch structures on DC and RF performances of AlGaN/GaN high electron mobility transistors*

“…[1][2][3][4][5][6] And many methods have been introduced to improve the high power characteristics, among them the field plate is adopted most. [7][8][9][10][11] There are many types of field plate structures, such as conventional gate field plate, [9,[12][13][14] , recessed gate field plate, [15] and Γ-gate with air bridge structure. [16,17] The field plate structure aims to reduce the peak electric field beside the gate electrode, eventually improve the breakdown characteristic.…”