Several approaches have been studied for microwave material processing for solar energy utilization such as upgrading the photocatalytic activity of TiO2, and improvement of efficiency in polymer solar cell. Recently, we observed the emission of zinc and oxygen plasmas from ZnO ceramics during intense absorption of microwaves as well as the deposition of zinc and zinc oxide films. This finding may lead to development of simple microwave-based methods for preparing thin-film ZnO, an alternative of ITO thin-film, from ZnO ceramics. The mid-infrared free electron laser-based system is also proposed to investigate the mechanism of interaction between microwave and wide-gap semiconducting materials. © Springer 2011.