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A p-type polycrystalline Ge (poly-Ge) film processed by UV and CO2 laser annealing reduces the hole concentration from 6 × 1018 to 2 × 1016 cm−3, accompanied by poly-grain growth. The decrease in hole concentration arises from the defect annealing using a CO2 laser, as demonstrated by the changes in the work function, that is, the valence-band maximum (VBM). The laser processes reduce the thermal budget for the fabrication of an enhancement-mode poly-Ge nMOSFET, which has a I on/I off ratio of 5 × 103, a V th of 2 V, and a subthreshold swing of 250 mV/dec., and will be potential fabrication methods for monolithic 3D integrated circuits in the future.

A low-thermal-budget n-type polycrystalline Ge (poly-Ge) channel that was prepared by plasma in-situ-doped nanocrystalline Ge (nc-Ge) and visible pulsed laser annealing exhibits a high electrically active concentration of 2 × 1019 cm−3 and a narrow Raman FWHM of 3.9 cm−1. Furthermore, the fabricated n-type poly-Ge junctionless FinFET (JL-FinFET) shows an I on/I off ratio of 6 × 104, V th of −0.3 V, and a subthreshold swing of 237 mV/dec at V d of 1 V and DIBL of 101 mV/V. The poly-Ge JL-FinFET with a high-aspect-ratio fin channel is less sensitive to V th roll-off and subthreshold-swing degradation as the gate length is scaled down to 50 nm. This low-thermal-budget JL-FinFET can be integrated into three-dimensional sequential-layer integration and flexible electronics.