Thermochemistry of MgB2 thin film synthesis

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 300°C 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 (∼37 K) by pulsed laser deposition (PLD).