Boron films produced by high energy Pulsed Laser Deposition

TL;DR

This paper reports on the production of micron-thick boron films via high-energy Pulsed Laser Deposition, analyzing their structure, properties, and potential for technological applications.

Contribution

It introduces a high-energy pulsed laser method for depositing smooth, low-oxygen boron films with detailed structural and mechanical characterization.

Findings

Films are amorphous with low oxygen uptake.

Crystallinity improves at temperatures above 800°C.

Films exhibit specific elastic and hardness properties.

Abstract

Micron-thick boron films have been deposited by Pulsed Laser Deposition in vacuum on several substrates at room temperature. The use of high energy pulses (>700 mJ) results in the deposition of smooth coatings with low oxygen uptake even at base pressures of 10$^{-4}$ - 10$^{-3}$ Pa. A detailed structural analysis, by X-Ray Diffraction and Raman, allowed to assess the amorphous nature of the deposited films as well as to determine the base pressure that prevents boron oxide formation. In addition the crystallization dynamics has been characterized showing that film crystallinity already improves at relatively low temperatures (800 {\deg}C). Elastic properties of the boron films have been determined by Brillouin spectroscopy. Finally, micro-hardness tests have been used to explore cohesion and hardness of B films deposited on aluminum, silicon and alumina. The reported deposition strategy allows the growth of reliable boron coatings paving the way for their use in many technology fields.