Thermochemistry of MgB2 Thin Film Synthesis

TL;DR

This paper investigates the thermodynamic and kinetic factors affecting MgB2 thin film synthesis, demonstrating that in-situ thermal processing can improve film quality and superconductivity despite high-temperature challenges.

Contribution

It provides new insights into overcoming kinetic barriers in MgB2 film growth, enabling higher quality superconducting films via pulsed laser deposition.

Findings

High transition temperature (37K) MgB2 films achieved

Large kinetic barrier prevents MgB2 decomposition at high temperatures

In-situ thermal processing enhances film crystallinity and superconductivity

Abstract

We have investigated the thermodynamic and kinetic barriers involved in the synthesis of MgB2 films. This work refines our initial conjectures predicting optimal MgB2 thin film growth conditions as a consequence of the unusually large kinetic barrier to MgB2 decomposition. The small Mg sticking coefficient at temperatures greater than 300C prevents high temperature synthesis with traditional vacuum growth methods. However, as a result of the large kinetic barrier to MgB2 decomposition, in-situ thermal processing can be used to enhance the crystallinity and the superconductivity of MgB2 films. We used these methods to produce MgB2 thin films with relatively high transition temperatures (37K) by pulsed laser deposition (PLD).