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A reliable and efficient small-signal parameter extraction method for GaN HEMTs
摘要： In this paper, a reliable and efficient parameter extraction method for GaN high electron mobility transistor (HEMT) small‐signal models has been proposed. By utilizing parameter scanning method, the initial values of the extrinsic elements are first extracted from the cold pinch‐off and cold unbiased measurement conditions, respectively. An iterative optimization algorithm is employed then to optimize the extrinsic elements. This scanning and iteration combined algorithm based on a direct extraction method of extrinsic elements can reduce the impact of the approximation error, which makes the determined values of the small‐signal parameters more reliable. The extraction flow has been realized in a Matlab program for efficiency. A 16‐element small‐signal equivalent circuit model (SSECM) for GaN HEMTs has been employed, and the new parameter extraction method has been validated by comparing the simulated small‐signal S‐parameters with the measured data from 0.1 GHz to 40 GHz for two different device dimensions.
关键词： small‐signal modeling,parameter extraction,GaN high electron mobility transistor (HEMT)
更新于2025-09-23 15:23:52
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Gate Conduction Mechanisms and Lifetime Modeling of p-Gate AlGaN/GaN High-Electron-Mobility Transistors
摘要： The gate conduction mechanisms in p-gallium nitride (GaN)/AlGaN/GaN enhancement mode transistors are investigated using temperature-dependent dc gate current measurements. In each of the different gate voltage regions, a physical model is proposed and compared to experiment. At negative gate bias, Poole–Frenkel emission (PFE) occurs within the passivation dielectric from gate to source. At positive gate bias, the p-GaN/AlGaN/GaN “p-i-n” diode is in forward operation mode, and the gate current is limited by hole supply at the Schottky contact. At low gate voltages, the current is governed by thermionic emission with Schottky barrier lowering in dislocation lines. Increasing the gate voltage and temperature results in thermally assisted tunneling (TAT) across the same barrier. An improved gate process reduces the gate current in the positive gate bias region and eliminates the onset of TAT. However, at high positive gate bias, a sharp increase in current is observed originating from PFE at the metal/p-GaN interface. Using the extracted conduction mechanisms for both devices, accurate lifetime models are constructed. The device fabricated with the novel gate process exhibits a maximum gate voltage of 7.2 V at t1% = 10 years.
关键词： time-dependent breakdown (TDB),p-GaN gate,high-electron-mobility transistor (HEMT),enhancement mode,gallium nitride (GaN),Conduction mechanism
更新于2025-09-23 15:21:21
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Simulation Investigation of Laterally Downscaled N-Polar GaN HEMTs
摘要： The N-polar GaN high-electron mobility transistors (HEMTs) have demonstrated a powerful performance as the Ga-polar GaN HEMTs. This investigation aims to show the direct current performance and cutoff frequency (fT) of the planar N-polar GaN HEMTs with gate lengths downscaling from 4 μm to 50 nm by 2-D device simulation. The impacts of traps and gate dielectrics and the roles of the ?eld-dependent mobility and the source and drain series resistances are investigated. For our central-gated device with a 10-nm top GaN channel layer, a 30-nm Al0.3Ga0.7N barrier layer, and a 3-nm Al2O3 gate dielectric, the gate length (LG) as the transition point from the long-channel behavior to the short-channel one is found to be 200 nm. For LG < 200 nm, a linear fT versus LG relation shows up, and notable short-channel effects appear, i.e., the negative shift of the threshold voltage, the increase of the drain-induced barrier lowering, and the almost LG-independent constant maximum transconductance in the saturation region. The degradation of the fT × LG product with the decrease in the aspect ratio between LG and the equivalent gate-channel distance (tt) is shown to be quite small. The LG/tt ratio for 15% degradation of the fT × LG product from its upper limit (19.23 GHz · μm) is 5.5. This small degradation of the frequency characteristics in short-channel devices is attributed to the quite small fringing capacitance of the gate.
关键词： short-channel effect,laterally scaling,N-polar GaN,High-electron mobility transistor (HEMT)
更新于2025-09-12 10:27:22
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[IEEE 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - Paris, France (2019.9.30-2019.10.1)] 2019 14th European Microwave Integrated Circuits Conference (EuMIC) - HEMT Small-Signal Modelling for Voltage-Controlled Attenuator Applications
摘要： Multi-bias measured and simulated S parameters are presented to validate the extension of an accurate on/off state HEMT switch small-signal modelling procedure to analog attenuator applications. Good agreements between measured and simulated multi-bias S parameters of the HEMT with a gate resistor are achieved by using only a common-gate real test-structure (without the gate resistor), which not only confirm the validity of the modelling for both digital and analog attenuator applications, but also validate the applicability of the capacitance network and extraction methods under more bias conditions.
关键词： small-signal model,voltage-controlled attenuator (VCA),high electron-mobility transistor (HEMT),monolithic microwave integrated circuit (MMIC)
更新于2025-09-12 10:27:22
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Hybrid Analog/Digital Linearization of GaN HEMT-Based Power Amplifiers
摘要： In this paper, we describe a hybrid analog/digital linearization scheme for GaN high-electron-mobility transistor (HEMT)-based power ampli?ers that consists of a novel analog feedforward circuit and a conventional generalized memory polynomial (GMP) digital predistorter (DPD). The analog circuit implements a nonlinear ?lter that compensates the long-term memory effects observed in GaN HEMTs due to the self-biasing behavior caused by electron-trapping phenomena. Experimental tests demonstrate that this linearization scheme achieves a level of intermodulation distortion 6.8 dB better than what can be achieved with just the use of the GMP DPD. This level of distortion is in compliance with the linearity speci?cations for multicarrier Global System for Mobile communications base station transmitters.
关键词： Analog linearization,long-term memory effects,GaN high-electron-mobility transistor (HEMT),power ampli?er (PA) linearization,digital predistortion (DPD),electron trapping
更新于2025-09-09 09:28:46
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Vertical Current Transport in AlGaN/GaN HEMTs on Silicon: Experimental Investigation and Analytical Model
摘要： We investigate the vertical leakage mechanism in metal–organic chemical vapor deposition-grown carbon (C)-doped AlGaN/GaN High Electron Mobility Transistors (HEMTs) on 6-in silicon wafer. Substrate bias polarity-dependentI–Vs, temperature-dependent ?tting, and band diagram analysis pointed to the Poole–Frenkel (P–F) type of conduction mechanism for vertical transport in the devices with breakdown as high as 580 V for a buffer of 4 μm. Trap activation energy of 0.61 eV was estimated from the P–F ?tting which matches well with values reported in the literature. We propose that higher dislocation density leads to shallower traps in the buffer and build an analytical model of dislocation-mediated vertical leakage around this. The variation in leakage as a function of dislocation density at a given ?eld is predicted and is found to be the most abrupt in the range from ～107 to ～109 cm?2 of dislocation density. This can be attributed to a sharp decrease in trap activation energy in the above range of dislocation density, possibly due to complex formation between point defects and dislocations.
关键词： high-electron mobility transistor (HEMT),vertical leakage,Poole–Frenkel (P–F),2-D electron gas,hopping conduction,AlGaN
更新于2025-09-09 09:28:46
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Full W-Band GaN Power Amplifier MMICs Using a Novel Type of Broadband Radial Stub
摘要： In this paper, we describe the design of the first reported full W-band (75–110 GHz) power amplifier (PA) monolithic microwave integrated circuits (MMICs) based on gallium nitride technology. The discussed MMICs come in two versions. Over a bandwidth (BW) of 70–110 GHz, the three-stage PA can deliver, on average, 25.6 dBm with a power-added efficiency (PAE) of 6.5%, while the four-stage PA is able to generate 27 dBm with a PAE of 6.1%. A peak output power of 28.6 dBm is achieved at 80 GHz with a PAE of 8.6%, which corresponds to a power density of 2.6 W/mm. The significant BW was achieved partially by incorporating a novel type of broadband radial stub into the design, which can provide nearly a twofold rejection-BW improvement over the conventional version. To the best of our knowledge, no other solid-state circuit can deliver such power levels over the complete W-band.
关键词： monolithic microwave integrated circuit (MMIC),Broadband,power amplifier (PA),high-electron-mobility transistor (HEMT),W-band (75–110 GHz),radial stub,gallium nitride,millimeter-waves (mm-waves)
更新于2025-09-09 09:28:46
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The Effect of Proton Irradiation in Suppressing Current Collapse in AlGaN/GaN High-Electron-Mobility Transistors
摘要： Almost complete suppression of dynamic ON-resistance in AlGaN/GaN high-electron-mobility transistors is obtained by proton irradiation. In this paper, both small and large power transistors are characterized before and after 3-MeV proton irradiation at different fluences. The irradiated devices show a high robustness and for specific fluences unaltered threshold voltage and static ON-resistance. However, for fluences higher than 1013 cm?2, the dynamic ON-resistance is almost completely suppressed at 600 V and T = 150 °C. After irradiation, a measurable increase in OFF-state leakage current is observed, indicating an increase in the unintentionally doped (UID) GaN layer conductivity. We propose a technology computer-aided design supported model in which this conductivity increase leads to an increased deionization rate, ultimately reducing the dynamic ON-resistance.
关键词： high-electron-mobility transistor (HEMT),proton irradiation,Gallium nitride (GaN),dynamic ON-resistance
更新于2025-09-09 09:28:46