Schottky-barrier thin-film transistors based on HfO2-capped InSe

Yiming Wang,Jiawei Zhang,Yanpeng Shi,Zakhar D Kovalyuk,Qian Xin,Yifei Zhang,Aimin Song,Guangda Liang,Amalia Patanè,Zakhar R Kudrynskyi

doi:10.1063/1.5096965

Abstract

Indium selenide (InSe) is an emerging two-dimensional semiconductor and a promising candidate for next generation thin film transistors (TFTs). Here, we report on Schottky barrier TFTs (SB-TFTs) in which a 0.9-nm-thick HfO2 dielectric layer encapsulates an InSe nanosheet, thus protecting the InSe-channel from the environment and reducing the Schottky-contact resistance through a dielectric dipole effect. These devices exhibit a low saturation source-drain voltage Vsat &lt; 2 V and current densities of up to J = 2 mA/mm, well suited for low-power electronics. We present a detailed analysis of this type of transistor using the Y-function method from which we obtain accurate estimates of the contact resistance and field-effect mobility.

Highlights

We report on Schottky barrier thin film transistors (TFTs) (SB-TFTs) in which a 0.9-nm-thick HfO2 dielectric layer encapsulates an Indium selenide (InSe) nanosheet, protecting the InSe-channel from the environment and reducing the Schottky-contact resistance through a dielectric dipole effect
The contact resistance can be modified by the insertion of an intermediate ultrathin dielectric layer, such as h-BN, Ta2O5, and TiO2.17–19 The Schottky barrier height at the metal-2D layer interface is effectively reduced by the high-k dielectric layer through a dielectric dipole effect.[20]
We report on the fabrication and electrical properties of SB-TFTs based on InSe

Summary

Introduction

These devices exhibit a low saturation source-drain voltage Vsat < 2 V and current densities of up to J 1⁄4 2 mA/mm, well suited for low-power electronics. We present a detailed analysis of this type of transistor using the Y-function method from which we obtain accurate estimates of the contact resistance and field-effect mobility. We estimate the field effect-mobility (l0 1⁄4 83.7 cm2/V s) and contact resistance (Rc 1⁄4 200 kX lm) of the SB-TFT using the Yfunction method (YFM).

Results

Conclusion