Investigation of LaAlO3-SrTiO3 field-effect transistors under hydrostatic pressure

Abstract

We have manufactured oxide field-effect transistors using the electron system at the LaAlO3-SrTiO3 interface as a drain-source channel and measured the devices under a hydrostatic pressure of up to 1.8 GPa. These studies of oxide transistors in the high-pressure regime demonstrate remarkable stability of the devices against gate leakage and resilience to mechanical strain. They show that oxide transistors can be operated in a wide range of pressures and temperatures and open the road for future studies of oxide materials and their possible applications in electronics.

Stimulating Oxide Heterostructures: A Review on Controlling SrTiO3‐Based Heterointerfaces with External Stimuli

“…Mechanical strain was also found to be highly effective in tuning especially the electron mobility and the carrier density . When mechanically straining La‐doped STO by approximately 0.3% using a three‐point bending device, the electron mobility at low temperatures was found to increase by 300% as shown in Figure .…”

“…The population of electrons in these bands then reduces the average effective mass and suppresses interband scattering . The LAO/STO interface and field effect transistors made hereof were shown to exhibit an increase in the carrier density, decrease of the mobility, and change in the transistor behavior upon application of hydrostatic pressure …”

Manifold field effects at a complex oxide interface

“…The fourth option, topgating, is closest to metal-oxide-semiconductor (MOS) devices that currently dominate the electronics industry. Such devices can be made to function on a small scale, work in wide ranges of temperature (147,158) and pressure (159), and can be operated with voltages comparable to MOS devices, allowing integration with stateof-the-art semiconductor technology. The thin layer of LaAlO 3 itself is an excellent gate dielectric, owing to its wide band gap of 5.6 eV and its high relative permittivity of 18 − 30 (76,160).…”

“…Among the few reports in literature on topgating patterned LaAlO 3 -SrTiO 3 channels, different topgate materials are used: YBa 2 Cu 3 O 7-δ (147,170), Au (55,143,152,158,159,(170)(171)(172), or Pt (173). Using YBa 2 Cu 3 O 7-δ has the advantage of reducing the intrinsic carrier density in the channel, raising the threshold voltage of field-effect devices closer to zero (145,147).…”

“…The issue is therefore usually settled in the middle, with a moderate LaAlO 3 thickness of the order of 10 unit cells (u.c. ), or ∼4 nm (98,143,152,158,159,(170)(171)(172)(173). Yet, pushing the limits of low gate currents in LaAlO 3 -SrTiO 3 devices with metal topgates remains an interesting challenge, which can result in studying the electric field effect in quantum matter heterostructures to a greater extent.…”