Suspended two-dimensional electron gases in In0.75Ga0.25As quantum wells

Abstract

We demonstrate that In 0:75 Ga 0:25 As quantum wells can be freely suspended without losing electrical quality when the epitaxial strainrelieving buffer layer is removed. In applied magnetic fields, non-dissipative behavior is observed in the conductivity, and a current induced breakdown of the quantum Hall effect shows a lower critical current in the suspended layers due to efficient thermal isolation compared to the non-suspended-control device. Beyond the critical current, background impurity scattering in the suspended two-dimensional channel regions dominates with stochastic, resonant-like features in the conductivity. This device fabrication scheme offers the potential for thermally isolated devices containing suspension-asymmetry-induced, high spin-orbit coupling strengths with reduced electron-phonon interaction behavior but without introducing high levels of disorder in the processing.

Suspended semiconductor nanostructures: physics and technology

“…Due to the lack of heat removal directly through the substrate, overheating of the sample, and thus the QHE breakdown, are achieved at lower heating currents, which is consistent with the bootstraptype electron heating model [184]. Furthermore, it was found that beyond the critical current, background impurity scattering in the suspended 2D channel regions leads to stochastic, resonant-like features appearing in the conductivity before the onset of the Ohmic regime [179].…”

“…In addition to the AlGaAs/GaAs samples, suspended structures with a high mobility 2DEG in InGaAs/InAlAs heterostructures were created [178]. In these structures, vanishings of the longitudinal magnetoresistance and the corresponding quantization plateaus in the Hall resistance at temperatures below 1.6 K were found [179].…”

“…Investigation of electron transport in quantizing magnetic fields also included the study of nonlinear effects, namely, the breakdown of QHE by a direct current [180,181], in a suspended 2DEG based on GaAs/AlGaAs [79] and InGaAs/InAlAs [179] heterostructures. The measurements were carried out in fixed magnetic fields corresponding to the integer filling factors, when the longitudinal resistance is zero.…”

Calculation and design of GaAs quantum dot devices where the vibrational modes can be frozen out at cryogenic temperatures

“…The above properties of the micro/nano electromechanical oscillators have been utilised in both simulations and experimentally in organic and inorganic structures [13][14][15][16][17][18][19][20][21]. Currently there is a growing interest in trying to observe many body localisation in solids state systems (MBL) [21].…”

“…The above properties of the micro/nano electromechanical oscillators have been utilised in both simulations and experimentally in organic and inorganic structures [13][14][15][16][17][18][19][20][21]. Currently there is a growing interest in trying to observe many body localisation in solids state systems (MBL) [21]. MBL can result in non-ergodic behaviour where disorder combined with electron-electron interactions can lead to regions of a device where the electrons states remain out of equilibrium with the rest of the device.…”