Enhancement of both direct-current and microwave characteristics of AlGaN∕GaN high-electron-mobility transistors by furnace annealing

Abstract

The enhancement of both direct-current (dc) and microwave characteristics of AlGaN∕GaN high-electron-mobility transistors (HEMTs) were demonstrated by conventional furnace annealing at 400°C for 5min. Due to the improvement in Ni∕Au Schottky contact properties by furnace annealing, about 17%, 34%, 23%, and 25% of enhancements in maximum drain current density, maximum extrinsic transconductance (gmmax), cutoff frequency and maximum oscillation frequency were observed, respectively. A positive threshold voltage shift and the increase in gmmax can also be correlated to the improved Schottky parameters such as ideality factor and barrier height. The annealed devices exhibited low reverse gate-leakage-current by more than three orders of magnitude and low drain-leakage-current by two orders of magnitude. Correspondingly, the devices exhibited 55% of higher breakdown voltage after annealing. The furnace annealing is an effective and viable means to enhance both dc and microwave characteristics of AlGaN∕GaN HEMTs.

Effect of gate-source and gate-drain Si3N4 passivation on current collapse in AlGaN∕GaN high-electron-mobility transistors on silicon

“…14,15 Si 3 N 4 with thickness of 120 nm was deposited by silane/ NH 3 -based plasma enhanced chemical vapor deposition at 300°C. Si ͑111͒ substrates.…”

Studies on plasma assisted molecular beam epitaxial growth of GaN-based multilayer heterostructures on Si for photodetector application

“…MBE technique has been used to grow III-V materials for more than 20 years. Both MBE [15][16][17][18][19] and MOCVD [20][21][22][23][24] can provide good quality epitaxy layers. While MOCVD provides faster deposition rate, MBE can provide sharper interface.…”

“…AlGaN layer with 30% Al-composition was grown and optimized on Si (111) substrate, AlN template deposited in-house by MOCVD and commercial AlN template. All AlGaN layer growths were optimized to achieve smooth surface morphology with similar RMS roughness of 0.8 nm regardless of the bottom substrate.Si doped AlGaN layers exhibited free carrier concentration of 1×1019 , 5×1019 , 1×1020 and 2×10 20 cm −3 , for the Si cell temperatures 1190 °C, 1250 °C, 1280 °C and 1310 °C, respectively. To the best of our knowledge, the value of 2×10 20 cm −3 obtained is much higher than reported free carrier concentration achieved in Si doped 30% AlGaN layer on Si by PA-MBE technique.…”

Studies of traps in AlGaN/GaN high electron mobility transistors on silicon

“…were extracted from the small-signal microwave characteristics [186] in order to investigate the parasitic effects introduced by the low-k dielectric BCB encapsulation layer. The DC output/transfer and the small signal parameters of four devices with and without BCB encapsulation measured across the wafer for uniformity analysis has been tabulated in Table 7.2.…”