Heteroepitaxial vertical perovskite hot-electron transistors down to the monolayer limit

Takeaki Yajima,Brian S. Y. Kim,Harold Y. Hwang,Yasuyuki Hikita

doi:10.1038/s41467-019-13290-3

Abstract

Two-dimensional heterostructures combined with vertical geometries are candidates to probe and utilize the physical properties of atomically-thin materials. The vertical configuration enables a unique form of hot-carrier spectroscopy as well as atomic-scale devices. Here, we present the room-temperature evolution of heteroepitaxial perovskite hot-electron transistors using a SrRuO3 base down to the monolayer limit (∼4 Å). As a fundamental electronic probe, we observe an abrupt transition in the hot-electron mean free path as a function of base thickness, coinciding with the thickness-dependent resistive transition. As a path towards devices, we demonstrate the integrated synthesis of perovskite one-dimensional electrical edge contacts using water-soluble and growth-compatible Sr3Al2O6 hard masks. Edge-contacted monolayer-base transistors exhibit on/off ratios reaching ∼108, complete electrostatic screening by the base manifesting pure hot-electron injection, and excellent scaling of the output current density with device dimensions. These results open new avenues for incorporating emergent phenomena at oxide interfaces and in heterostructures.

Highlights

Two-dimensional heterostructures combined with vertical geometries are candidates to probe and utilize the physical properties of atomically-thin materials
Hot-electron spectroscopy[11] would be an invaluable tool to investigate the nanometer scale electronic reconstructions that are often observed at interfaces and in confined geometries[7]
In pursuit of this approach, we demonstrate the evolution of a highly robust vertical hot-electron transistor (HET)[12] based on perovskite oxide heterostructures down to the monolayer-base limit, consisting of a SrTiO3 emitter, atomically thin SrRuO3 base, and Nb:SrTiO3 (001) collector (Fig. 1; see the Methods section)

Summary

Introduction

Two-dimensional heterostructures combined with vertical geometries are candidates to probe and utilize the physical properties of atomically-thin materials. In pursuit of this approach, we demonstrate the evolution of a highly robust vertical hot-electron transistor (HET)[12] based on perovskite oxide heterostructures down to the monolayer-base limit, consisting of a SrTiO3 emitter (both Nb-doped and undoped), atomically thin SrRuO3 base, and Nb:SrTiO3 (001) collector (Fig. 1; see the Methods section).

Results

Conclusion