Tunable Doping and Mobility Enhancement in 2D Channel Field-Effect Transistors via Damage-Free Atomic Layer Deposition of AlOX Dielectrics

TL;DR

This paper introduces a scalable plasma-enhanced atomic layer deposition method for damage-free aluminum oxide dielectrics on 2D materials, enabling precise doping control and mobility enhancement in 2D FETs, advancing their integration in electronics.

Contribution

The study presents a novel PEALD process for non-damageable AlOX dielectric deposition on 2D materials, allowing systematic doping tuning and mobility improvements in 2D FETs.

Findings

Successful damage-free AlOX deposition confirmed by Raman spectroscopy.

Tuning of Dirac and threshold voltages in graphene and MoS₂ FETs.

Enhanced charge carrier mobility and high breakdown fields in devices.

Abstract

Two-dimensional materials (2DMs) have been widely investigated because of their potential for heterogeneous integration with modern electronics. However, several major challenges remain, such as the deposition of high-quality dielectrics on 2DMs and the tuning of the 2DM doping levels. Here, we report a scalable plasma-enhanced atomic layer deposition (PEALD) process for direct deposition of a nonstoichiometric aluminum oxide (AlOX) dielectric, overcoming the damage issues associated with conventional methods. Furthermore, we control the thickness of the dielectric layer to systematically tune the doping level of 2DMs. The experimental results demonstrate successful deposition without detectable damage, as confirmed by Raman spectroscopy and electrical measurements. Our method enables tuning of the Dirac and threshold voltages of back-gated graphene and MoS${_2}$ field-effect transistors (FETs), respectively, while also increasing the charge carrier mobility in both device types. We further demonstrate the method in top-gated MoS${_2}$ FETs with double-stack dielectric layers (AlOX+Al${_2}$O${_3}$), achieving critical breakdown field strengths of 7 MV/cm and improved mobility compared with the back gate configuration. In summary, we present a PEALD process that offers a scalable and low-damage solution for dielectric deposition on 2DMs, opening new possibilities for precise tuning of device characteristics in heterogeneous electronic circuits.