Thermochemistry of MgB/sub 2/ thin film synthesis

We have investigated the thermodynamic and kinetic barriers involved in the synthesis of MgB/sub 2/ films. This work refines our initial conjectures predicting optimal MgB/sub 2/ thin film growth conditions as a consequence of the unusually large kinetic barrier to MgB/sub 2/ decomposition. The small Mg sticking coefficient at temperatures greater than 300/spl deg/C prevents high temperature synthesis with traditional vacuum growth methods. However, as a result of the large kinetic barrier to MgB/sub 2/ decomposition, in-situ thermal processing can be used to enhance the crystallinity and the superconductivity of MgB/sub 2/ films. We used these methods to produce MgB/sub 2/ thin films with relatively high transition temperatures (/spl sim/37 K) by pulsed laser deposition (PLD).