연구홍보포털

논문 초록 (Abstract)

Bilayer channel engineering was investigated as a means of balancing current transport and switching in indium zinc oxide (IZO) thin-film transistors (TFTs). Bottom-gate bottom-contact devices with Mo source/drain electrodes were fabricated using 20 nm single-layer IZO deposited at Ar/O2 flow rates of 50/0, 40/10, and 30/20 sccm, together with a bilayer comprising a 10 nm lower layer deposited at 50/0 sccm and a 10 nm upper layer deposited at 30/20 sccm. All devices were post-annealed in air at 300 ℃. The 50/0 single layer remained conductive without a clear off-state, whereas oxygen addition enabled gate-controlled switching. The 30/20 device exhibited low current and pronounced backward-sweep distortion. The bilayer reduced this distortion while exhibiting a turn-on voltage of -5.80 V, a subthreshold swing of 0.79 V dec-1, and a linear field-effect mobility of 29.31 cm2 V-1 s-1. Its mobility was 5.33 times that of IZO (30/20) and comparable to 31.48 cm2 V-1 s-1 for IZO (40/10). At VG = 20 V and VD = 0.1 V, the bilayer current was 1.57 times that of IZO (40/10). The apparent total source/drain series resistances were 36.5, 167.2, and 7.73 kΩ for IZO (40/10), IZO (30/20), and the bilayer, respectively. The bilayer thus combined higher current and lower apparent series resistance with gate-controlled switching, although its turn-on voltage and subthreshold swing were not improved relative to IZO (40/10). These results support a conductive contact-facing layer as part of a gate-modulated bilayer channel. Suppression of Mo oxidation remains a possible interpretation rather than a directly established mechanism.