Strain- and temperature-induced effects in AlGaN/GaN high electron mobility transistors

Yalamarthy, Ananth Saran; Senesky, Debbie G.

doi:10.1088/0268-1242/31/3/035024

Cited by 30 publications

(12 citation statements)

References 48 publications

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“…[16] The average conductivity in the thin GaN sample is observed to be similar to the bulk GaN sample due to simultaneous reduction in the sheet density and quantum well depth, as seen in Figure 4a. Sheet densities in this temperature range are approximately constant due to negligible strain relaxation in the heterostructure layers, [37] stable piezoelectric coefficients, [22] and minimal intrinsic carrier concentration change due to the wide-bandgap. Thus, the decrease of σ at high temperatures is mainly determined by the 2DEG mobility, μ.…”

Section: Electrical and Thermal Property Measurementsmentioning

confidence: 99%

Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering

Yalamarthy

Rojo

et al. 2018

Adv Funct Materials

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Over the last decade, progress in wide bandgap, III-V materials systems based on gallium nitride (GaN) has been a major driver in the realization of high power and high frequency electronic devices. Since the highly conductive, two-dimensional electron gas (2DEG) at the AlGaN/GaN interface is based on built-in polarization fields (not doping) and is confined to very small thicknesses, its charge carriers exhibit much higher mobilities in comparison to their doped counterparts. In this study, we show that this heterostructured material also offers the unique ability to manipulate electrical transport separately from thermal transport through the examination of fully-suspended AlGaN/GaN diaphragms of varied GaN buffer layer thicknesses. Notably, we show that ~100 nm thin GaN layers can considerably impede heat flow without electrical transport degradation, and that a significant improvement (~4x) in the thermoelectric figure of merit (zT) over externally doped GaN is observed in 2DEG based heterostructures. We also observe state-of-the art thermoelectric power factors (4-7×10 -3 Wm -1 K -2 at room temperature) in the 2DEG of this material system. This remarkable tuning behavior and thermoelectric enhancement, elucidated here for the first time in a polarization-based heterostructure, is achieved since the electrons are at the heterostructured interface, while the Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering

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Section: Electrical and Thermal Property Measurementsmentioning

confidence: 99%

Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering

Yalamarthy

Rojo

et al. 2018

Adv Funct Materials

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“…Figure 4 shows the change in current passing through the 2DEG with respect to applied displacement (i.e., strain). External strain through applied displacement induces additional piezoelectric polarization of the 2DEG [13], changes in surface traps [14], and alters the Schottky barrier height [15]. Therefore, there was an increase in current when the membrane was gradually deflected from 13 μm to 106.7 μm.…”

Section: Experimental Methodsmentioning

confidence: 99%

Lithography-free microfabrication of AlGaN/GaN 2DEG strain sensors using laser ablation and direct wire bonding

Dowling

Toor

et al. 2017

Microelectronic Engineering

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This work presents a simple and rapid lithography-free (i.e., maskless) microfabrication process for strain-sensitive aluminum gallium nitride (AlGaN)/GaN sensors. We microfabricated an AlGaN/GaN strain sensor through laser ablation of the underlying Si (111) substrate and direct bonding of aluminum wires to the AlGaN surface, creating a Schottky contact to the twodimensional electron gas (2DEG). We measured the sensor's current-voltage operation while displacing the center of the membrane up to 106.7 μm and characterized its sensitivity at from 0.5 to 2 V bias (i.e., 5 to 100 nA/μm). This work advances the development of AlGaN/GaN-on-Si microelectronics (e.g., pressure sensors, accelerometers, and gyroscopes) using the simplified fabrication process, which eliminates lithography, metallization, and etching, and reduces the manufacturing time (5 min) and cost, as well as the need for cleanroom environments.

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“…Previous studies demonstrate that 2DEG can be affected by strain [8]. Tong et al [9] applied a strain model to study the electron transport in normally-on HEMT device when barrier is uniformly biaxial strained.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Electrical Characteristics on Inhomogeneous Strains in Normally-off HEMTs with p-GaN Gate

et al. 2020

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Strain is one of the important factors affecting the two-dimensional electron gas (2DEG) transform in AlGaN/GaN material based high electron mobility transistors (HEMTs) by polarization effects. In this paper, the effects of inhomogeneous biaxial strain in different regions of the AlGaN barrier layer on electrical properties of normally-off HEMTs with p-GaN gate were discussed. The results show that biaxial strain applied in three regions has different influence on transfer, output and breakdown characteristics of the device. The strain applied in region under gate has the most significant impact on threshold voltage and drain saturation current with a decreasing of 39% and an increasing of 97% respectively as the strained lattice constant increases from 3.173061Å to 3.187229Å.While, strain applied between gate and drain electrode can improve the off-state breakdown voltage by 12% with the increasing of strained lattice constant.

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Strain- and temperature-induced effects in AlGaN/GaN high electron mobility transistors

Cited by 30 publications

References 48 publications

Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering

Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering

Lithography-free microfabrication of AlGaN/GaN 2DEG strain sensors using laser ablation and direct wire bonding

Simulation of Electrical Characteristics on Inhomogeneous Strains in Normally-off HEMTs with p-GaN Gate

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