Vertical stacking and lateral growth of molybdenum disulfide (MoS ) are controlled with remarkable precision, and MoS nanotubes are directly converted from nanofibers. Predictive synthesis is enabled by identifying the specific thermodynamic region where the Boudouard reaction becomes favored. It reveals how the chemical potential of each species in the MoSCO system can predict phase behaviors.

The phase development and defect formation during the silicidation reaction of sputter-deposited Er films on Si with ∼20-nm-thick Ta and TaN capping layers were examined. TaN capping effectively prevented the oxygen incorporation from the annealing atmosphere, which resulted in complete conversion to the ErSi2-x phase. However, significant oxygen penetration through the Ta capping layer inhibited the ErSi2-x formation, and incurred the growth of several Er-Si-O phases, even consuming the ErSi2-x layer formed earlier. Both samples produced a number of small recessed defects at an early silicidation stage. However, large rectangular or square-shaped surface defects, which were either pitlike or pyramidal depending on the capping layer identity, were developed as the annealing temperature increased. The origin of different defect generation mechanisms was suggested based on the capping layer-dependent silicidation kinetics.

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This study examined the effects of the Zn ratio on the microstructure of InGaZnO (IGZO) films and the device performance of their transistors. IGZO films with various Zn ratios were produced by co-sputtering InGaO and ZnO at different ZnO powers. The combination of transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses elucidated that as the Zn ratio increased from 0 to 0.69, the microstructure changed from amorphous IGZO to nanocrystalline IGZO and then to columnar ZnO. The dynamic transitions of the microstructure, in turn, profoundly affected the electrical properties including the mobility and carrier concentration. The sample with a mixing ratio of 0.25:0.2:0.55 (In:Ga:Zn) exhibited the best performance with a mobility of nearly 30 cm 2 /VÁs. Transparent oxide semiconductors (TAOS) have recently gained much attention owing to their technologically important features, including their high electron mobility, high transparency, capability for low temperature processing, etc. These materials are excellent candidates for the active layer of thin film transistors for display applications. 1,2 In particular, amorphous InGaZnO 4 (IGZO) has been the focus of many research and development efforts since Hosono and colleagues first demonstrated the possibility of using it as the active layer of TFTs. 3 Some such studies include the optimization of sputtering conditions (O 2 pressure, sputtering power, etc) and post-annealing conditions. 1,4 Nevertheless, systematic composition engineering of this material by modulating the cation ratio still remains incomplete.For the development of IGZO-based transistors with enhanced device performance, it is important to understand the roles of the main metallic elements (In, Ga, and Zn) of the material. Some recent studies unfolded that as the In ratio increased, the carrier concentration escalated sensitively and thus led to an increase in both the on-current and off-current, suggesting that In played the role of charge carrier generators. 5,6 Increasing the Ga ratio seems to have the opposite effect: With the Ga content increasing, the carrier concentration drastically decreases since Ga suppresses oxygen vacancy formation. 5-10 Thus, the In/Ga ratio is known to be critical for determining the carrier concentration of IGZO films. However, what remains relatively unexplored are the effects of modulating the Zn ratio on the film properties. It would be intriguing to investigate how the microstructure evolves and the electrical properties change as the Zn ratio changes over a wide range.In this study, we delved into the effects of the Zn ratio on the characteristics (microstructure, carrier concentration, and Hall mobility) of IGZO films and the device performance of their TFTs. We produced IGZO films with various Zn ratios via co-sputtering InGaO (IGO) and ZnO at different ZnO target powers. Combining X-ray diffraction (XRD), transmission electron microscopy (TEM), and Hall Effect measurements helped us to fully characterize the evolution of the film microstruct...

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