Bottom gate single crystal Si thin-film transistors fabricated by all sputtering processes

Abstract

Single-crystal Si (c-Si) bottom-gate thin-film transistors (BG-TFTs) were fabricated using all sputtering processes. Laser doping from sputter-deposited Sb-doped amorphous Si film was proposed, by which n+ c-Si with resistivity and contact resistivities of 1.5 × 10−3 Ωcm and 2.1 × 10−5 Ωcm2, respectively, were fabricated. In addition, thin (50 nm) and low-heat conductive titanium was proposed for BG to realize continuous lateral crystal growth in Si film above the edge of BG. The fabricated n-channel c-Si BG-TFTs exhibited a field-effect mobility of 75 ± 21 cm2 V−1s−1, subthreshold swing of 0.612 ± 0.110 Vdec−1, and threshold voltage of 4.9 ± 1.38 V. Lack of bottom Si/SiO2 interface quality was indicated to be the origin of insufficient mobility.