Laser optothermal nanobomb for efficient flattening of nanobubbles in van der Waals materials

TL;DR

This paper introduces a laser optothermal nanobomb (LOTB) technique that effectively flattens nanobubbles in 2D van der Waals materials, significantly improving surface quality without damaging the material, and enabling better device fabrication.

Contribution

The study presents the first post-processing laser method, LOTB, for removing nanobubbles in 2D materials, enhancing surface smoothness and device reliability.

Findings

Surface roughness reduced by over 70% within 50 ms.

LOTB does not damage the intrinsic properties of 2D materials.

Dual-beam and multi-shot strategies improve flattening efficiency.

Abstract

Nanobubbles are typical nanodefects commonly existing in two-dimensional (2D) van der Waals materials such as transition metal dioxides, especially after their transfer from growth substrate to target substrates. These nanobubbles, though tiny, may significantly alter the local electric, optoelectronic, thermal, or mechanical properties of 2D materials and therefore are rather detrimental to the constructed devices. However, there is no post-processing method so far that can effectively eliminate nanobubbles in 2D materials after their fabrication and transfer, which has been a major obstacle in the development of 2D material based devices. Here, we propose a principle, called laser optothermal nanobomb (LOTB), that can effectively flatten nanobubbles in 2D materials through a dynamic process of optothermally induced phase transition and stress-pulling effect in nanobubbles. Operation of LOTB on monolayer molybdenum disulfide (1L-MoS2) films shows that the surface roughness can be reduced by more than 70% on a time scale of ~50 ms, without damage to the intrinsic property of 1L-MoS2 as validated by micro-nano photoluminescence and Raman spectroscopy. Moreover, a dual-beam cascaded LOTB and a multi-shot LOTB strategies are proposed to increase the flattened area and processing effect, showing the potential of LOTB for fast nanodefect repairing in the mass production of van der Waals materials and devices.