High-temperature electron transport properties in AlGaN/GaN heterostructures

Abstract

Electron transport properties in the Al0.15Ga0.85N/GaN heterostructure field effect transistors (HFETs) have been examined from room temperature up to 400 °C. The temperature dependencies of the two-dimensional electron gas (2DEG) mobility have been systematically measured for the samples with different 2DEG densities. The 2DEG mobility has been shown to decrease with increasing the temperature, with the lower decrease ratio at higher temperatures, and moreover, shown to be less dependent on the 2DEG density at higher temperatures. These features well agree with those of the longitudinal optical phonon-limited mobility theoretically predicted, although the effect of alloy and interface scattering should further be examined and analyzed. The observed 2DEG mobilities at 400 °C were as high as from 100 to 120 cm2/V s, directly providing the evidence for suitability of the HFET of this material system for high-temperature applications. Moreover, Si-doped Al0.15Ga0.85N single layer has been shown to exhibit a relatively high bulk mobility of 50 cm2/V s at 400 °C, suggesting that AlGaN is attractive as the channel material when higher-voltage and higher-temperature device operation is required.

Superior suppression of gate current leakage in Al2O3/Si3N4 bilayer-based AlGaN/GaN insulated gate heterostructure field-effect transistors

“…where n R is the ideality factor under reverse bias, q the electronic charge, and J RS the reverse saturation current given by J RS ϭ A*T 2 exp(Ϫqφ TH B /K B T) (2) in which φ TH B is the Schottky barrier height, and A* the effective Richardson constant.…”

“…[1][2][3][4] Record output power density of more than 30 W/mm at microwave frequency has been reported, 5 demonstrating the good potential for commercial applications. The device with superior pinch-off characteristics at high temperatures up to 400°C has been demonstrated as well for the applications at high temperatures.…”

Improved electrical properties of the two-dimensional electron gas in AlGaN/GaN heterostructures using high temperature AlN interlayers

“…Because of their unusual combination of physical properties, AlGaN/GaN-based high electron mobility transistors have shown a great deal of promise in high-power, high-temperature, and high-frequency electronics, and continue to receive much research and development interest [1,2]. The main benefits of the AlGaN/GaN heterostructures for microwave power HEMTs reside with the high 2DEG density resulting from strong spontaneous and piezoelectric polarization induced electrical fields associated with the large conduction band offset between AlGaN and GaN compared with that in AlGaAs/GaAs heterostructures.…”

High-temperature transport properties of 2DEG in AlGaN/GaN heterostructures

“…[1][2][3] The high operating temperature is a prominent advantage of Al x Ga 1ÿx N/GaN-based devices over Al x Ga 1ÿx As/GaAs-based devices. Although Daumiller et al 4 evaluated the stability of AlGaN/ GaN HEMTs under high-temperature stress up to 800°C, the self-heating effect in AlGaN/GaN heterostructures due to low thermal conductivity of the sapphire substrate has been demonstrated to strongly limit device performance.…”