Temperature simulation at ZnO surface processed by laser interference lithography

ZnO thin film on alumina has been deposited by RF sputtering and processed by two dimensional direct laser interference patterning (DLIP) using a nanosecond laser (λ=355nm). The thermodynamic and structural properties have been investigated. Morphological characterization has shown a line-pattern structure with small alterations depending on the fluence of the laser (85 mJ/cm2 or 165 mJ/cm2). In order to understand these modifications, a simulation has been carried out to model the transient temperature during the DLIP to study the temperature reached by the ZnO surface for the different fluences. Moreover, a comparison with a non-interference energy distribution pulse is also simulated to corroborate the model. For samples processed by DLIP, a thermal annealing effect has been noticed when temperatures at the surface are between 1000K and 1800K. Due to the slow cooling process, a possible recrystallization of the material similar to a thermal treatment is obtained. For temperatures close or higher than 1800K, the material starts to ablate.