Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition

Gene Siegel,Megan C Prestgard,Y P Venkata Subbaiah,Ashutosh Tiwari

doi:10.1063/1.4921580

Abstract

We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS2 target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 °C in an ambient vacuum of 10−6 Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM), Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL) measurements. The ablation of the MoS2 target by 50 laser pulses (energy density: 1.5 J/cm2) was found to result in the formation of a monolayer of MoS2 as shown by AFM results. In the Raman spectrum, A1g and E12g peaks were observed at 404.6 cm−1 and 384.5 cm−1 with a spacing of 20.1 cm−1, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV) and 615 nm (2.02 eV), with a...

Highlights

We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique
It was found that the ablation of MoS2 target with 50 laser pulses results in a film thickness of about 6.5 Å, which corresponds to a single monolayer of MoS2
Since in the first part of our study we found that the ablation by 50 laser pulses results in the formation of one monolayer, we used integral multiples of 50 laser pulses to grow bi-layer, tri-layer, and few-layer MoS2 films

Summary

Introduction

We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition The ablation of the MoS2 target by 50 laser pulses (energy density: 1.5 J/cm2) was found to result in the formation of a monolayer of MoS2 as shown by AFM results.

Results

Conclusion