Ultrashort Pulse Laser Annealing of Amorphous Atomic Layer Deposited MoS$_2$ Films

TL;DR

This study demonstrates that ultrashort pulse laser annealing can effectively transform amorphous ALD-grown MoS$_2$ films into crystalline structures, enabling controlled pattern formation without high-temperature processing.

Contribution

It introduces a novel ultrashort pulse laser method for crystallizing amorphous MoS$_2$ films deposited by atomic layer deposition, with detailed analysis of process parameters and resulting morphologies.

Findings

Successful crystallization of amorphous MoS$_2$ with ultrashort laser pulses

Formation of self-organized patterns during laser annealing

Comparison shows advantages over thermal and cw laser annealing

Abstract

Thin films of molybendum disulfide grown via thermal atomic layer deposition at low temperatures, suitable for temperature sensible substrates, can be amorphous. To avoid a high temperature post treatment of the whole sample, which can cause thermal degradation of the substrate or other layers, a ultrashort pulse (usp) laser-induced transformation to crystalline layers is one of the most promising routes. In this paper we report the crystallization of amorphous MoS$_2$ layers processed with ultrashort laser pulses. The amorphous MoS$_2$ films were deposited by atomic layer deposition (ALD) and exposed to picosecond laser pulses ($\lambda = 532$ nm). The crystallization and the influence of the processing parameters on the film morphology were analyzed in detail by Raman spectroscopy and scanning electron microscopy. Furthermore, a transition of amorphous MoS$_2$ by laser annealing to self-organized patterns is demonstrated and a possible process mechanism for the ultrashort pulse laser annealing is discussed. Finally, the usp laser annealed films were compared to thermally and continuous wave (cw) laser annealed samples.