Person:

Kim, Sang Bok

Bottom-gate thin film transistors with amorphous zinc tin oxide channels were grown by atomic layer deposition (ALD). The films maintained their amorphous character up to temperatures over 500 (^{\circ})C. The highest field effect mobility was ~13 (cm^2/V^.s) with on-to-off ratios of drain current ~10(^9)-10(^{10}). The lowest subthreshold swing of 0.27 V/decade was observed with thermal oxide as a gate insulator. The channel layers grown at 170 (^{\circ})C showed better transistor properties than those grown at 120 (^{\circ})C. Channels with higher zinc to tin ratio (~3-4) also performed better than ones with lower ratios (~1-3).

Atomic layer deposition (ALD) of tin oxide ((SnO_2)) thin films was achieved using a cyclic amide of Sn(II) (1,3-bis(1,1-dimethylethyl)-4,5-dimethyl-(4R,5R)-1,3,2-diazastannolidin-2-ylidene) as a tin precursor and nitric oxide (NO) as an oxidant gas. Film properties as a function of growth temperature from (130-250^{\circ}C) were studied. Highly conducting (SnO_2) films were obtained at (200-250^{\circ}C) with the growth per cycle of (~1.4 \mathring{A})/cycle, while insulating films were grown at temperatures lower than (200^{\circ}C). Conformal growth of (SnO_2) in holes of aspect-ratios up to ~50 : 1 was successfully demonstrated.