Trap-state density in continuous-wave laser-crystallized single-grainlike silicon transistors

This investigation characterizes electrical characteristics of continuous-wave green laser-annealed single-grainlike silicon thin-film transistors in relation to trap-state densities. As laser power increases, highly crystalline channels form, reducing tail-state densities to as low as 3×1019eV−1cm−3. This occurrence is responsible for high field-effect electron mobility of 284cm2∕Vs. In contrast, increasing laser power initially reduces the deep-state density and then increases it to 3×1016eV−1cm−3. This reversal in deep-state density and thus in the subthreshold slope as well as a saturating reduction in threshold voltage are associated with the formation of extra interface defects caused by laser-crystallization-enhanced surface roughness.