Superheating of thin films for optical recording

Two methods for calculating the temperature in a thin film on a substrate during laser exposure are discussed. A simple algebraic expression gives a satisfactory estimate for the maximum temperature if radial diffusion of heat is negligible. A numerical method is applied to calculate the temperature profile in a tellurium film on a PMMA substrate. The calculations show that for pulse times below about 10 μs, the temperature at which hole opening occurs, is considerably above the melting point of tellurium. This indicates that for small pulses the solid film is locally superheated due to the limiting kinetics of the melting process.