Nanoscale rapid melting and crystallization of semiconductor thin films.

The current study details nanosecond laser-based rapid melting and crystallization of thin amorphous silicon (a-Si) films at the nanoscale using two different optical near-field processing schemes. Both apertureless and tapered fiber near-field scanning optical microscope probes were utilized to deliver highly confined irradiation on the target surface. The various modification regimes produced as a result of the rapid a-Si melting and crystallization transformations were shown to critically depend on the applied laser fluence. Consequently, the crystallized pattern morphology and feature size could be finely controlled. High energy density was observed to impart ablation surrounded by a narrow melt ring. At much lower incident laser energy density, single nanostructures with a lateral dimension of approximately 90 nm were defined.