Abstract
This study presents the optimization of the lateral device geometry and thickness of the channel and barrier layers of AlGaN/GaN high electron mobility transistors (HEMTs) for the enhancement of breakdown voltage (VBR) characteristics using a TCAD simulation. The effect of device geometry on the device performance was explored by varying the device design parameters, such as the field plate length (LFP), gate-to-drain length (LGD), gate-to-source length (LGS), gate length (LG), thickness of the Si3N4 passivation layer (Tox), thickness of the GaN channel (Tch), and AlGaN barrier (Tbarrier). The VBR was estimated from the off-state drain current versus the drain voltage (IDS–VDS) curve, and it exhibited a strong dependence on the length and thickness of the parameters. The optimum values of VBR for all the device’s geometrical parameters were evaluated, based on which, an optimized device geometry of the field-plated AlGaN/GaN HEMT structure was proposed. The optimized AlGaN/GaN HEMT structure exhibited VBR = 970 V at IGS = 0.14 A/mm, which was considerably higher than the results obtained in previous studies. The results obtained in this study could provide vital information for the selection of the device geometry for the implementation of HEMT structures.
Highlights
AlGaN/GaN high-electron mobility transistors (HEMTs) have attracted extensive attention for high-frequency and high-voltage applications owing to their excellent properties, such as the high electron mobility of their two-dimensional electron gas (2-DEG) channels, their wide energy band-gap, and their high breakdown field [1,2]
Based on the simulation results, we propose an AlGaN/GaN HEMT structure with optimized device geometry to achieve the best possible device performance in terms of VBR
The optimized device design parameters obtained from the simulation in this study provide a potential guideline for the development of high-performance AlGaN/GaN HEMTs
Summary
AlGaN/GaN high-electron mobility transistors (HEMTs) have attracted extensive attention for high-frequency and high-voltage applications owing to their excellent properties, such as the high electron mobility of their two-dimensional electron gas (2-DEG) channels, their wide energy band-gap, and their high breakdown field [1,2]. To enhance the device’s performance for high-voltage power devices and microwave applications, GaN-based HEMTs were developed using field-plate technology, through which tremendous improvements in the VBR and power densities were demonstrated [1,12,13,14,15,16]. The field plate is an extension of the gate deposited onto the passivation layer toward the drain side to minimize the electric field at the AlGaN surface. This leads to a reduction in the DC-to-RF dispersion, resulting in an increase in the VBR [17]. They reported an optimum VBR of 880 V at a gate current of 40 A/mm for the best field plate case
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