Laser-Induced Gas-Phase Transfer and Direct Stamping of Nanomaterials: Comparison of Nanosecond and Femtosecond Pulses

TL;DR

This study compares nanosecond and femtosecond laser pulses for transferring hexagonal boron nitride nanomaterials, revealing different transfer mechanisms and optimal conditions for clean, efficient, and reproducible nanomaterial stamping.

Contribution

It introduces a laser-induced transfer method for hBN using both femtosecond and nanosecond pulses, analyzing their effects on transfer efficiency and quality.

Findings

Transfer occurs via direct stamping at short distances.

Nanosecond pulses enable successful line printing.

Femtosecond pulses can cause titanium transfer with molten debris.

Abstract

The two-dimensional nanomaterial, hexagonal boron nitride (hBN) was cleanly transferred via a blister-based laser-induced forward-transfer method. The transfer was performed utilizing femtosecond and nanosecond laser pulses for separation distances of ~16 and ~200 micrometers between a titanium donor film deposited on a glass substrate and a silicon/silicon dioxide receiver. Transfer efficiency was examined for isolated laser pulses as well as for series of overlapping pulses and single layer transfer was confirmed. It was found that hBN is transferable for all tested combinations of pulse duration and transfer distances. The results indicate that transfer proceeds via direct stamping for short donor-to-receiver distances while, for the larger distance, the material is ejected from the donor and lands on the receiver. Furthermore, with overlapping pulses, nanosecond laser pulses enable a successful printing of hBN lines while, for fs laser pulses, the Ti film can be locally disrupted by multiple pulses and molten titanium may be transferred along with the hBN flakes. For reproducibility, and to avoid contamination with metal deposits, low laser fluence transfer with ns pulses and transfer distances smaller than the blister height provide the most favourable and reproducible condition.