Uniform Growth of Sub-5-Nanometer High-κ Dielectrics on MoS2 Using Plasma-Enhanced Atomic Layer Deposition.

Journal Article

Regardless of the application, MoS2 requires encapsulation or passivation with a high-quality dielectric, whether as an integral aspect of the device (as with top-gated field-effect transistors (FETs)) or for protection from ambient conditions. However, the chemically inert surface of MoS2 prevents uniform growth of a dielectric film using atomic layer deposition (ALD)-the most controlled synthesis technique. In this work, we show that a plasma-enhanced ALD (PEALD) process, compared to traditional thermal ALD, substantially improves nucleation on MoS2 without hampering its electrical performance, and enables uniform growth of high-κ dielectrics to sub-5 nm thicknesses. Substrate-gated MoS2 FETs were studied before/after ALD and PEALD of Al2O3 and HfO2, indicating the impact of various growth conditions on MoS2 properties, with PEALD of HfO2 proving to be most favorable. Top-gated FETs with high-κ films as thin as ∼3.5 nm yielded robust performance with low leakage current and strong gate control. Mechanisms for the dramatic nucleation improvement and impact of PEALD on the MoS2 crystal structure were explored by X-ray photoelectron spectroscopy (XPS). In addition to providing a detailed analysis of the benefits of PEALD versus ALD on MoS2, this work reveals a straightforward approach for realizing ultrathin films of device-quality high-κ dielectrics on 2D crystals without the use of additional nucleation layers or damage to the electrical performance.

Full Text

Duke Authors

Cited Authors

  • Price, KM; Schauble, KE; McGuire, FA; Farmer, DB; Franklin, AD

Published Date

  • July 2017

Published In

Volume / Issue

  • 9 / 27

Start / End Page

  • 23072 - 23080

PubMed ID

  • 28653822

Electronic International Standard Serial Number (EISSN)

  • 1944-8252

International Standard Serial Number (ISSN)

  • 1944-8244

Digital Object Identifier (DOI)

  • 10.1021/acsami.7b00538

Language

  • eng