Effect of external strain on the conductivity of AlGaN/GaN high-electron-mobility transistors

Abstract

The changes in the conductance of the channel of Al0.3Ga0.7N/GaN high-electron-mobility transistor structures during the application of both tensile and compressive strain were measured. For a fixed Al mole fraction, the changes in the conductance were roughly linear over the range up to 2.7×108 N cm−2, with coefficients for planar devices of −6.0+/−2.5×10−10 S N−1 m−2 for tensile strain and +9.5+/−3.5×10−10 S N−1 m−2 for compressive strain. For mesa-isolated structures, the coefficients were smaller due to the reduced effect of the AlGaN strain, with values of 5.5+/−1.1×10−13 S N−1 m−2 for tensile strain and 4.8×10−13 S N−1 m−2 for compressive strain. The large changes in the conductance demonstrate that simple AlGaN/GaN heterostructures are promising for pressure and strain sensor applications.

Laser ablation for membrane processing of AlGaN/GaN- and micro structured ferroelectric thin film MEMS and SiC pressure sensors for extreme conditions

“…As a result, the HEMT conductivity can be influenced by external strain. Thus HEMTs based on AlGaN/GaN heterostructures have appeared to be preferable candidates for pressure sensing 3,4 loading was investigated and also verified. Functionality of the proposed circular diaphragms was evaluated at room temperature and low static and dynamic pressure loading 8 .…”

“…These concepts are based on conductance measurement and/or on nitride film deflection. Usually, the change in the density of the 2-dimensional electron gas (2DEG) confined at the AlGaN/GaN interface as a consequence of the applied strain is presented 3,4 as the main reason for this phenomena. In the fabrication process of the proposed MEMS sensors the key and highly important issue is the creation of appropriate diaphragms necessary for the verification of their multi-sensing properties.…”

Piezoelectric polarization-induced two dimensional electron gases in AlGaN/GaN heteroepitaxial structures: Application for micro-pressure sensors

“…Due to the large energy bandgap and high melting temperature, optoelectronic devices based on this material system have advantages over the conventional AlGaAs/GaAs and InGaAsP/InP material systems at high temperature and high power performances [1]. Furthermore, the strong piezoelectric polarization property along the [0 0 0 1] orientation makes it a better candidate for pressure sensitive devices [1][2][3][4][5][6][7][8] than the GaAs based structures. Since these devices can be made using the thin heterostructure membranes by removing locally the substrate with the present state-of-theart micro-fabrication technologies, sensors in the micrometer scale are possible.…”

Performance Enhancement of Flip-Chip Packaged AlGaN/GaN HEMTs Using Active-Region Bumps-Induced Piezoelectric Effect

“…The channel conductance of AlGaN/GaN HEMTs had been proved increased during the application of tensile stress, whereas decreased during the application of compressive stress [3]. In reference [4], the biaxial tensile stress induced by thick Si 3 N 4 passivation contributed to the increase of sheet charge density leading to an increase of 11.5% in the maximum drain current compared to unpassivated devices.…”