Enthalpy of formation for Cu-Zn-Sn-S (CZTS)

Herein we report an analytical procedure to calculate the enthalpy of formation for thin film multinary compounds from sputtering rates measured during ion bombardment. The method is based on Sigmund's sputtering theory and the Born-Haber cycle. Using this procedure, an enthalpy of formation for a CZTS film of the composition Cu$_{1.9}$Zn$_{1.5}$Sn$_{0.8}$S$_4$ was measured as -930$\pm$98 kJ/mol. This value is much more negative than the sum of the enthalpies of formation for the constituent binary compounds, meaning the multinary formation reaction is predicted to be exothermic.