Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 22: 2D Materials and their Heterostructures I (joint session DS/HL/O)

HL 22.1: Talk

Tuesday, March 17, 2020, 09:30–09:45, CHE 89

Plasma-enhanced atomic layer deposition of AlN at 40^∘C for encapsulation and dielectric integration of 2D materials — •Michele Bissolo, Alex Henning, Theresa Grünleitner, and Ian D. Sharp — Walter Schottky Institute, 85748 Garching, Germany

To date, hexagonal boron nitride (h-BN) is the material of choice for the dielectric integration of 2D materials since it preserves the intrinsic photoluminescence yield, charge carrier mobility, and band gap of 2D semiconductors by reducing strain, effects of interfacial defects, and remote phonons. However, h-BN must be either mechanically transferred with a polymer stamp onto a bulk substrate, which introduces contamination, or grown by MBE at temperatures above 800^∘C, which is incompatible with BEOL, microlithography, and temperature-sensitive materials. Here, we demonstrate atomically flat aluminum nitride (AlN), grown by plasma-enhanced atomic layer deposition (PEALD) at 40^∘C, as a scalable alternative to h-BN. AlN has a similar band gap (E_g = ∼6 eV) and a larger dielectric constant (є = ∼9) in comparison to h-BN. Because ALD is conformal, it enables the full enclosure of the 2D material. In this work, we test PEALD AlN as a substrate and encapsulation layer for mono- and few-layer MoS₂. Raman spectroscopy suggests a strain-free integration of MoS₂ with AlN and photoluminescence shows a relatively stronger emission from the A and B excitons without emission from defects. We demonstrate the improved fieldeffect mobility with MoS₂ field-effect transistors enclosed by an AlN dielectric layer. This work provides a scalable route to the dielectric integration of 2D materials critical for future optoelectronics.