Piezoelectricity-Induced Schottky Barrier Height Variations in AlGaN/GaN High Electron Mobility Transistors

Yao, Kaiyuan; Khandelwal, Sourabh; Sammoura, Firas; Kazama, Atsushi; Hu, Chenming; Lin, Lung–Huang

doi:10.1109/led.2015.2456178

Cited by 28 publications

(15 citation statements)

References 16 publications

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“…This could be related to an increased surface state density as a result of strain induced defects when bending is applied, which offsets the strain effect on the Schottky barrier height. 23,24 The change in the 2DEG density Dn s is then simplified as a change in polarization charge Dr pol during bending. Dr pol can be calculated as ÀDr pol ¼ r Á ðDP pz Þ, 25 where DP pz , which is the additional piezoelectric polarization field during 1D bending, can be calculated as…”

mentioning

confidence: 99%

Modulation of the two-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending

Wang

Chen

Lundh

et al. 2020

Applied Physics Letters

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We investigate the effect of strain on the two-dimensional electron gas (2DEG) channel in a flexible Al 0.25 Ga 0.75 N/GaN high-electron-mobility transistor (HEMT) by mechanical bending to prove the concept of active polarization engineering to create multifunctional electronic and photonic devices made of flexible group III-nitride thin films. The flexible HEMTs are fabricated by a layer-transfer process and integrated with a 150-lm-thick Cu film. The strain values are estimated from high-resolution x-ray diffraction and Raman spectroscopy in 4-cm bend-down and À4-cm bend-up test conditions. The strain-induced piezoelectric polarization can alter the charge density of the 2DEG in the channel at the AlGaN/GaN interface and thus modify the output characteristics of the flexible HEMTs. Accordingly, output characteristics show an increase in output current by 3.4% in the bend-down condition and a decrease by 4.3% in the bend-up condition. Transfer characteristics show a shift of threshold voltage, which also supports the 2DEG channel modulation during bending. Computational simulation based on the same structure confirms the same current modulation effect and threshold voltage shift. Furthermore, the electrical characteristics of the flexible HEMTs show a repeatable dependence on the strain effect, which offers potential for electro-mechanical device applications.

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confidence: 99%

Modulation of the two-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending

Wang

Chen

Lundh

et al. 2020

Applied Physics Letters

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“…The temperature-dependent transient behavior can be explained by the existence of two traps (caused by material defects) in different locations in the AlGaN/GaN heterostructure (Figure 4). If the trap is at the top surface of the AlGaN and above the Fermi level, the trap will be pulled below the Fermi level upon application of compressive strain due to a reduction in Schottky barrier height [5]. This causes a reduction in the 2DEG concentration and the current.…”

Section: Resultsmentioning

confidence: 99%

TEMPERATURE-DEPENDENT TRANSIENT BEHAVIOR OF AlGaN/GaN HIGH ELECTRON MOBILITY PRESSURE SENSORS

Chapin¹,

Dowling²,

Phan³

et al. 2018

2018 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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For the first time, the time-dependent response of an AlGaN/GaN high electron mobility transistor (HEMT) pressure sensor is characterized at elevated temperatures. We show that temperature affects the sensitivity and the transient behavior of the sensor's response to pressure. At a temperature above 125°C, the drain current response after the application of pressure transitions from exponentially decaying to exponentially growing. Using an Arrhenius model of trap activation energy, we demonstrate that two traps in the AlGaN/GaN heterostructure at 0.62 eV and 0.87 eV cause the temperature-dependent transient behavior. This work paves the way for creating reliable GaN-based sensing devices.

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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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Piezoelectricity-Induced Schottky Barrier Height Variations in AlGaN/GaN High Electron Mobility Transistors

Cited by 28 publications

References 16 publications

Modulation of the two-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending

Modulation of the two-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending

TEMPERATURE-DEPENDENT TRANSIENT BEHAVIOR OF AlGaN/GaN HIGH ELECTRON MOBILITY PRESSURE SENSORS

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

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