Thin-film transistors based on spin-coated chalcogenide semiconductor channels
The production of high-performance solution-processed semiconductor films represents an important materials challenge, with achievement of field-effect mobilities >10 cm 2/V-sec being particularly desirable for high-speed low-cost microelectronic applications. While most soluble semiconductor research has focused on organic systems, this review addresses a hydrazinium precursor approach for solution-processing high-quality inorganic films. Ultrathin SnSe 2-xS x channel layers, spin coated from a hydrazine solution of chalcogenides, yield field-effect mobilities and on-off ratios as high as 12 cm 2/V-s and 10 6, respectively. Analogous devices have also been prepared from water-hydrazine solvent mixtures (20% hydrazine by volume), thereby reducing the concentration of highly toxic hydrazine during spin-coating. Additionally, In 2Se 3 channel layers have been demonstrated, spin coated without the use of hydrazine as solvent, yielding μ sat = 16.5 cm 2/V-s, μ lin = 4.9 cm 2/V-s, I on/I off = 10 6, with a subthreshold swing as low as S = 450 mV/decade. The operating voltages in these latter devices have been reduced to 8V through the use of a relatively thin (250 Å) SiO x gate insulator. Reductions in the use of hydrazine and in the TFT operating voltage improve fabrication and operational compatibility of the devices with respect to electronics industry standards.
