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The annealing temperature dependent electrical characteristics of La2O3 gate dielectrics for W gated AlGaN/GaN high electron mobility transistors (HEMTs) have been characterized. The threshold voltage (Vth) has been found to shift to positive direction with higher temperature annealing, exceeding those of Schottky HEMTs, presumably attributed to the presence of negative fixed charges at the interface between La2O3 and AlGaN layers. At a high temperature annealing over 500 °C, a high dielectric constant (k-value) of 27 has been achieved with poly-crystallization of the La2O3 film, which is useful to limit the reduction in gate capacitance. A high k-value for La2O3 gate dielectrics and the presence of negative charges at the interface are attractive for AlGaN/GaN HEMTs with low gate leakage and normally-off operation. 相似文献
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《Electron Devices, IEEE Transactions on》2009,56(12):2911-2916
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Performance of the AlGaN HEMT structure with a gate extension 总被引:5,自引:0,他引:5
Thompson R. Prunty T. Kaper V. Shealy J.R. 《Electron Devices, IEEE Transactions on》2004,51(2):292-295
The microwave performance of AlGaN/GaN HEMTs at large drain bias is reported. The device structures were grown by organometallic vapor phase epitaxy on SiC substrates with a channel sheet resistance less than 280 ohms/square. The breakdown voltage of the HEMT was improved by the composite gate structure consisting of a 0.35 /spl mu/m long silicon nitride window with a 0.18 /spl mu/m long metal overhang on either side. This produced an metal-insulator-semiconductor (MIS) gate extension toward the drain with the insulator, silicon nitride, approximately 40-nm-thick. Transistors with a 150 /spl mu/m total gate width have demonstrated a continuous wave (CW) 10 GHz output power density and power added efficiency of 16.5 W/mm and 47%, respectively when operated at 60 V drain bias. Small-signal measurements yielded an f/sub T/ and f/sub max/ of 25.7 GHz and 48.8 GHz respectively. Maximum drain current was 1.3 A/mm at +4 V on the gate, with a knee voltage of /spl sim/5 V. This brief demonstrates that AlGaN/GaN HEMTs with an optimized gate structure can extend the device operation to higher drain biases yielding higher power levels and efficiencies than have previously been observed. 相似文献
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Improved reliability of AlGaN-GaN HEMTs using an NH/sub 3/ plasma treatment prior to SiN passivation
Edwards A.P. Mittereder J.A. Binari S.C. Katzer D.S. Storm D.F. Roussos J.A. 《Electron Device Letters, IEEE》2005,26(4):225-227
A passivation method has been developed which reduces the degradation of AlGaN-GaN high electron mobility transistor (HEMT) electrical properties caused by extended dc bias or microwave power operation. The key aspect of this passivation technique is exposure to a low-power NH/sub 3/ plasma prior to SiN deposition. Devices fabricated with the NH/sub 3/ treatment prior to SiN passivation show minimal gate lag and current collapse after extended dc bias operation. In addition, the rate of degradation of the microwave power output while under continuous microwave operation is improved by at least 100 times as compared to SiN passivated HEMTs that were not treated with the NH/sub 3/ plasma. 相似文献
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《Electron Device Letters, IEEE》2009,30(5):427-429
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Trapping effects and microwave power performance in AlGaN/GaN HEMTs 总被引:14,自引:0,他引:14
Binari S.C. Ikossi K. Roussos J.A. Kruppa W. Doewon Park Dietrich H.B. Koleske D.D. Wickenden A.E. Henry R.L. 《Electron Devices, IEEE Transactions on》2001,48(3):465-471
The dc small-signal, and microwave power output characteristics of AlGaN/GaN HEMTs are presented. A maximum drain current greater than 1 A/mm and a gate-drain breakdown voltage over 80 V have been attained. For a 0.4 μm gate length, an fT of 30 GHz and an fmax of 70 GHz have been demonstrated. Trapping effects, attributed to surface and buffer layers, and their relationship to microwave power performance are discussed. It is demonstrated that gate lag is related to surface trapping and drain current collapse is associated with the properties of the GaN buffer layer. Through a reduction of these trapping effects, a CW power density of 3.3 W/mm and a pulsed power density of 6.7 W/mm have been achieved at 3.8 GHz 相似文献
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F等离子体处理工艺被广泛的应用于 AlGaN/GaN HEMT增强型器件的研制和栅前处理工艺。本文研究了低功率F处理 AlGaN/GaN HEMT的击穿特性和电流崩塌特性。随着F处理时间的增加,饱和电流下降,阈值电压正向移动。对不同F处理时间的器件肖特基特性分析后发现,120s的F处理后器件栅泄漏电流明显减小,器件击穿电压提高,当F处理时间大于120s后,由于长时间F处理带来的损伤器件栅泄漏电流没有继续减小。采用不同偏置下的双脉冲测试对不同F处理时间的电流崩塌特性进行了研究,低功率F处理后没有发现明显的电流崩塌现象。 相似文献
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M. Dammann W. Pletschen W. Bronner S. Müller O. Ambacher S. Murad R. Behtash K. Riepe E.Ö. Sveinbjörnsson 《Microelectronics Reliability》2009,49(5):474-477
Excellent reliability performance of AlGaN/GaN HEMTs on SiC substrates for next generation mobile communication systems has been demonstrated using DC and RF stress tests on 8 × 60 μm wide and 0.5 μm long AlGaN/GaN HEMTs at a drain voltage of Vd = 50 V. Drain current recovery measurements after stress indicate that the degradation is partly caused by slow traps generated in the SiN passivation or in the HEMT epitaxial layers. The traps in the SiN passivation layer were characterized using high and low frequency capacitance-voltage (CV) measurements of MIS test structures on thick lightly doped GaN layers. 相似文献
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A. Pérez-Tomás A. Fontserè M.R. Jennings P.M. Gammon 《Materials Science in Semiconductor Processing》2013,16(5):1336-1345
GaN-based high electron mobility transistors (HEMTs) with a Schottky metal gate have been demonstrated to be an excellent candidate for high frequency, high temperature and high power applications. Nevertheless, their typical (and virtually inevitable) high gate leakage current, severely limits gate voltage swing, output power and breakdown voltage. GaN metal–insulator –semiconductor HEMTs or MIS-HEMTs (formed by introducing a thin dielectric film between the gate metal and semiconductor) is one of the effective solutions that reduce gate leakage and improve device performance. In this work, we evaluate the effect that the introduction of this gate insulator has on the on-state of the HEMT. For this reason, we develop a complete set of compact closed-form expressions for the evaluation of on-resistance, drain and saturation current and transconductance for a MIS-HEMT. This physical-based model describes the mobility in a 2D electron gas channel by means of optical phonon scattering and is explored with insulators based on SiO2, SiNx, Al2O3, and HfO2. 相似文献
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Edge Effects on Gate Tunneling Current in HEMTs 总被引:1,自引:0,他引:1
We elucidate five considerations for accurate estimation of electron tunneling from the gate edges of high-electron mobility transistors (HEMTs). These considerations are listed as follows: 1) edge roughness; 2) net charge at the AlGaN/passivation interface; 3) dielectric constant of the medium above the HEMT surface; 4) nontriangular potential barrier; and 5) negligible angular tunneling from the gate edge. Using these considerations, we calculate the reverse gate current IG of AlGaN/GaN HEMTs based on thermionic trap-assisted tunneling (TTT) and direct tunneling (DT) mechanisms. These calculations establish that the observed rise in IG for a gate voltage beyond the threshold is due to tunneling from the gate edges. The calculations also show that the TTT mechanism can predict the measured IG of AlGaN/GaN HEMTs over a wide range of gate voltages and temperatures and point to the possibility of a rapid rise in IG at high gate voltages due to the DT mechanism. 相似文献
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High-performance enhancement-mode AlGaN/GaN HEMTs using fluoride-based plasma treatment 总被引:6,自引:0,他引:6
We report a novel approach in fabricating high-performance enhancement mode (E-mode) AlGaN/GaN HEMTs. The fabrication technique is based on fluoride-based plasma treatment of the gate region in AlGaN/GaN HEMTs and post-gate rapid thermal annealing with an annealing temperature lower than 500/spl deg/C. Starting with a conventional depletion-mode HEMT sample, we found that fluoride-based plasma treatment can effectively shift the threshold voltage from -4.0 to 0.9 V. Most importantly, a zero transconductance (g/sub m/) was obtained at V/sub gs/=0 V, demonstrating for the first time true E-mode operation in an AlGaN/GaN HEMT. At V/sub gs/=0 V, the off-state drain leakage current is 28 /spl mu/A/mm at a drain-source bias of 6 V. The fabricated E-mode AlGaN/GaN HEMTs with 1 /spl mu/m-long gate exhibit a maximum drain current density of 310 mA/mm, a peak g/sub m/ of 148 mS/mm, a current gain cutoff frequency f/sub T/ of 10.1 GHz and a maximum oscillation frequency f/sub max/ of 34.3 GHz. 相似文献
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The authors describe the current/voltage characteristic collapse under a high drain bias in AlGaN/GaN heterostructure insulated gate field effect transistors (HIGFETs) grown on sapphire substrates. These devices exhibit a low resistance state and a high resistance state, before and after the application of a high drain voltage, respectively. At room temperature, the high resistance state persists for several seconds. The device can also be returned into the low resistance state by exposing it to optical radiation. Electron trapping in the gate insulator near the drain edge of the gate is a possible mechanism for this effect, which is similar to what has been observed in AlGaAs/GaAs HFETs at cryogenic temperatures 相似文献
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Recessed-gate structure approach toward normally off high-Voltage AlGaN/GaN HEMT for power electronics applications 总被引:1,自引:0,他引:1
Saito W. Takada Y. Kuraguchi M. Tsuda K. Omura I. 《Electron Devices, IEEE Transactions on》2006,53(2):356-362
A recessed-gate structure has been studied with a view to realizing normally off operation of high-voltage AlGaN/GaN high-electron mobility transistors (HEMTs) for power electronics applications. The recessed-gate structure is very attractive for realizing normally off high-voltage AlGaN/GaN HEMTs because the gate threshold voltage can be controlled by the etching depth of the recess without significant increase in on-resistance characteristics. With this structure the threshold voltage can be increased with the reduction of two-dimensional electron gas (2DEG) density only under the gate electrode without reduction of 2DEG density in the other channel regions such as the channel between drain and gate. The threshold-voltage increase was experimentally demonstrated. The threshold voltage of fabricated recessed-gate device increased to -0.14 V while the threshold voltage without the recessed-gate structure was about -4 V. The specific on-resistance of the device was maintained as low as 4 m/spl Omega//spl middot/cm/sup 2/ and the breakdown voltage was 435 V. The on-resistance and the breakdown voltage tradeoff characteristics were the same as those of normally on devices. From the viewpoint of device design, the on-resistance for the normally off device was modeled using the relationship between the AlGaN layer thickness under the gate electrode and the 2DEG density. It is found that the MIS gate structure and the recess etching without the offset region between recess edge and gate electrode will further improve the on-resistance. The simulation results show the possibility of the on-resistance below 1 m/spl Omega//spl middot/cm/sup 2/ for normally off AlGaN/GaN HEMTs operating at several hundred volts with threshold voltage up to +1 V. 相似文献
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Sung Hwan Won Ji Ho Hur Chang Bin Lee Hyun Chul Nam Chung J.K. Jin Jang 《Electron Device Letters, IEEE》2004,25(3):132-134
We developed a high-performance, hydrogenated amorphous silicon thin-film transistor (a-Si:H TFT) on plastic substrate using an organic gate insulator. The TFT with a silicon-nitride (SiN/sub x/) gate insulator exhibited a field-effect mobility of 0.3 cm/sup 2//Vs and a threshold voltage of 5 V. On the other hand, an a-Si:H TFT with an organic gate insulator of BCB (benzocyclobutene) has a field-effect mobility of 0.4 cm/sup 2//Vs and a threshold voltage of 0.7 V. The leakage currents through the gate insulator of an a-Si:H TFT with an organic gate insulator is about two orders of magnitude lower than that of an a-Si:H TFT with a SiN/sub x/ gate insulator. 相似文献
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研究了SiN钝化前利用感应耦合等离子体(ICP)对AlGaN/GaN HEMT表面进行NF3等离子体处理对器件性能的影响. 结果表明,运用低能量的NF3等离子体处理钝化前的AlGaN/GaN HEMT表面能有效抑制器件电流崩塌,而器件直流及微波小信号特性则未受影响. 微波功率测试表明,经过6min NF3等离子体处理的AlGaN/GaN HEMT在2GHz, 30V工作电压下达到6.15W/mm的输出功率密度,而未经过处理的器件只达到1.82W/mm的输出功率密度. 相似文献
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基于凹槽栅增强型氮化镓高电子迁移率晶体管(GaN HEMT)研究了不同的栅槽刻蚀工艺对GaN器件性能的影响。在栅槽刻蚀方面,采用了一种感应耦合等离子体(ICP)干法刻蚀技术与高温热氧化湿法刻蚀技术相结合的两步法刻蚀技术,将AlGaN势垒层全部刻蚀掉,制备出了阈值电压超过3 V的增强型Al_2O_3/AlGaN/GaN MIS-HEMT器件。相比于传统的ICP干法刻蚀技术,两步法是一种低损伤的自停止刻蚀技术,易于控制且具有高度可重复性,能够获得更高质量的刻蚀界面,所制备的器件增强型GaN MIS-HEMT器件具有阈值电压回滞小、电流开关比(ION/IOFF)高、栅极泄漏电流小、击穿电压高等特性。 相似文献
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《Electron Device Letters, IEEE》2009,30(4):313-315