Photoluminescence in laser-crystallized polycrystalline silicon

Photoluminescence measurements were performed on thin laser-crystallized polycrystalline silicon (poly-Si) films at 5 K. The photoluminescence (PL) peak position and intensity depend on the crystallinity of the films. In fully crystallized films band-to-band recombination is observed at 1.16 eV. In partially crystallized samples a two-layer system arises with poly-Si on top of an amorphous layer. In this case the PL spectrum is determined by the amorphous silicon layer. None of the samples exhibits a detectable defect luminescence. The presence of hydrogen in the initially amorphous material does not affect the radiative emission of the fully crystallized poly-Si films. However, post-hydrogenation of poly-Si causes considerable enhancement of the PL intensity.