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Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistors with Graphene
摘要： A thermal analysis of AlGaN/GaN high electron mobility transistors (HEMTs) with Graphene is investigated using Silvaco and Finite Element Method. Two thermal management solutions are adopted; first of all, graphene is used as dissipation material between SiC substrate and GaN buffer layer to reduce thermal boundary resistance of the device. At the same time, graphene is also used as a thermal spread material on the top of the source contacts to reduce thermal resistance of the device. The thermal analysis results show that the temperature rise of device adopting graphene decreases by 46.5% in transistors operating at 13.86 W/mm. Meanwhile, the thermal resistance of GaN HEMTs with graphene is 6.8 K/W, which is much lower than the device without graphene, which is 18.5 K/W. The thermal management solutions are useful for integration of large-scale graphene into practical devices for effective heat spreading in AlGaN/GaN HEMT.
关键词： AlGaN/GaN,Thermal Management,High-Electron-Mobility Transistors (HEMTs),Graphene
更新于2025-09-23 15:23:52
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A voltage-transient method for characterizing traps in GaN HEMTs
摘要： Trapping e?ects in GaN HEMTs still limit their performance. The current-transient methodology has shown advantages in characterizing traps in the device. However, the voltage drift may cause errors in measurements with high accuracy requirements. In this paper, we present a methodology to characterize traps in GaN HEMTs using the voltage-transient measurements. We demonstrate the advantages of this method in terms of simplicity and e?ectiveness. In particular, it avoids the said problem due to the optimized measuring circuit. With this method, we have identi?ed the time constants and energy levels of traps in the AlGaN barrier layer and the GaN bu?er layer, respectively, in the devices. Their trapping and de-trapping mechanisms were also demonstrated at various temperature measurements. A classic exponential dependence of the degradation rate on the channel current was identi?ed.
关键词： Trapping e?ect,GaN,Voltage transient,High electron mobility transistors (HEMTs)
更新于2025-09-23 15:22:29
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Discrete-Pulsed Current Time Method to Estimate Channel Thermal Resistance of GaN-Based Power Devices
摘要： A simple electrical method to extract device channel thermal resistance in transistors is presented here. The method compares the dc to discrete-pulsed characteristics and estimates the effective increase in channel temperature under dc biasing conditions. Using the discrete-pulsed I versus t method, the self-heating of the device is effectively eliminated, which helps avoiding the underestimation of the device channel thermal resistance, therefore, making it possible to perform thermal measurements at the high power operation. This technique was applied to lateral GaN HEMTs with three different substrates as well as vertical GaN current aperture vertical electron transistor (CAVET) on sapphire, which proved its sensitivity and validity for different device structures and geometries.
关键词： high-electron mobility transistors (HEMTs),self-heating,current aperture vertical electron transistor (CAVET),Channel thermal resistance
更新于2025-09-23 15:21:01
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Analytical Gate Capacitance Models for Large-Signal Compact Model of AlGaN/GaN HEMTs
摘要： In this paper, analytical gate capacitance models for a large-signal compact model of AlGaN/GaN high-electron mobility transistors are proposed. Different from the MOSFET devices, different depletion regions on either side of the gate are fully considered for high-voltage GaN devices. The depletion regions are bias-dependent to implement the capacitance models into the large-signal compact model. A transfer function is proposed to characterize the switching behavior of the capacitances between on- and off-states, which is essential to describe all the states of a device, for example, operating at Class-B. Different from previous works, the current saturation phenomenon is taken into account in determining the intrinsic capacitances which are induced by nonstatic channel charge. The capacitance models can be easily implemented into the virtual-source-based model to accurately predict the S-parameters and large-signal output characteristics.
关键词： intrinsic capacitances,2-D electron gas (2DEG)-electrode fringing capacitances,AlGaN/GaN high-electron mobility transistors (HEMTs),large-signal compact model
更新于2025-09-09 09:28:46
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Creation of Two-Dimensional Electron Gas and Role of Surface Donors in III-N Metal-Oxide-Semiconductor High-Electron Mobility Transistors
摘要： The role of surface donors at the oxide/semiconductor interface of III-N metal-oxide-semiconductor (MOS) high-electron mobility transistors (HEMTs), by creating a two-dimensional electron gas (2DEG) and the device performance, are investigated. Al2O3/GaN/AlGaN/GaN MOS HEMTs show the surface donor density (Nd,surf ) of 2.2 (cid:1) 1013 cm(cid:3)2 which is increased up to 3.4 (cid:1) 1013 cm(cid:3)2 after post-deposition annealing. In the latter, surface donors fully compensate the surface polarization charge and the HEMT threshold voltage decreases substantially with the oxide thickness. On the other hand, an open-channel drain current is found to be independent of Nd,surf, while marginal trapping is completely removed when Nd,surf increases with annealing. Consequently, ionized surface donors behave like a fixed charge and are clearly distinguishable from trapping states. Open-channel 2DEG densities of (cid:4)1.1 (cid:1) 1013 cm(cid:3)2 are extracted from capacitance–voltage measurements. Similarly, recent data on enhancement-mode HfO2/InAlN/AlN/GaN MOS HEMTs are analyzed where Nd,surf is reduced down to (cid:3)2 while 2DEG densities reach (cid:4)2.7 (cid:1) 1013 cm(cid:3)2. It is suggested that under the open-channel condition, 2DEG is supplied also by an injecting source contact if Nd,surf is lower than the QW polarization charge. Our charge quantifications are supported by calculating energy-band diagrams.
关键词： oxide-semiconductor interfaces,AlGaN/GaN high-electron mobility transistors (HEMTs),polarization
更新于2025-09-09 09:28:46
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Model Development for Threshold Voltage Stability Dependent on High Temperature Operations in Wide-Bandgap GaN-Based HEMT Power Devices
摘要： Temperature-dependent threshold voltage (Vth) stability is a significant issue in the practical application of semi-conductor power devices, especially when they are undergoing a repeated high-temperature operation condition. The Vth analytical model and its stability are dependent on high-temperature operations in wide-bandgap gallium nitride (GaN)-based high electron mobility transistor (HEMT) devices that were investigated in this work. The temperature effects on the physical parameters—such as barrier height, conduction band, and polarization charge—were analysed to understand the mechanism of Vth stability. The Vth analytical model under high-temperature operation was then proposed and developed to study the measurement temperatures and repeated rounds dependent on Vth stability. The validity of the model was verified by comparing the theoretical calculation data with the experimental measurement and technology computer-aided design (TCAD) simulation results. This work provides an effective theoretical reference on the Vth stability of power devices in practical, high-temperature applications.
关键词： high-temperature operation,gallium nitride (GaN),analytical model,high electron mobility transistors (HEMTs),threshold voltage (Vth) stability
更新于2025-09-04 15:30:14