Electrically tunable nonvolatile 2D van der Waals p–n heterostructures based on GeSe-quasi 2D electron gas on the SrTiO3 surface

Abstract

Theoretical modulation of the current rectification ratio and turn-on voltage of p–n diodes by selecting semiconductor materials with appropriate Fermi levels remains challenging in practice. Key obstacles include lattice matching, thermal compatibility, and chemical stability during material synthesis. Most nonvolatile diodes are realized in ferroelectric systems, but size effects in ferroelectrics limit device miniaturization. In this work, we demonstrate an electrically tunable nonvolatile diode based on non-ferroelectric two-dimensional (2D) van der Waals heterostructures of GeSe and a quasi-2D electron gas on SrTiO3 surfaces. The device achieves a tunable current rectification ratio of 103–104 without gate bias application, with a continuously adjustable turn-on voltage from 0.1 to 2.1 V. Furthermore, the heterostructure demonstrates nonvolatile resistance switching behavior induced by applied bias voltage. The integration of electrical tunability and non-volatility in a single non-ferroelectric diode offers a promising platform for low-dimensional nonvolatile memory devices with multi-bit storage capability.