Electrostatic modulation of the lateral carrier density profile in field effect devices with nonlinear dielectrics

Eylon Persky, Hyeok Yoon, Yanwu Xie, Harold Y. Hwang, Jonathan Ruhman, Beena Kalisky

Research output: Contribution to journalArticlepeer-review

Abstract

The properties of two-dimensional (2D) electronic systems are often effectively controlled using electrostatic gating. The geometry of such field effect devices influences the effectiveness of the gate and the carrier density profile in the 2D device. Here, we analyze the gate-induced spatial variations in the lateral carrier density in patterned LaAlO3/SrTiO3 devices. We model the electrostatics of the 2D interface using the Thomas-Fermi approximation and compute the gate-induced charge distribution at the interface. We show that the electric field lines generated by the gate are focused at the edges of the device, causing an increased depletion near its edges. This effect is accentuated in LaAlO3/SrTiO3 due to the large, nonlinear dielectric constant of the substrate, and the large distance between the gate electrode and the interface. We experimentally demonstrate one consequence of this effect by directly imaging current distributions in gated heterostructures, finding that insulating regions nucleate at the edges of the device due to the gate. Our results suggest that device geometry and choice of dielectric materials control the charge distribution in 2D systems.

Original languageEnglish
Article number195427
JournalPhysical Review B
Volume107
Issue number19
DOIs
StatePublished - 15 May 2023

Bibliographical note

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© 2023 American Physical Society.

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