Improved electrical performance of a sol-gel IGZO transistor with high-k Al2O3 gate dielectric achieved by post annealing.

We have explored the effect of post-annealing on the electrical properties of an indium gallium zinc oxide (IGZO) transistor with an Al2O3 bottom gate dielectric, formed by a sol-gel process. The post-annealed IGZO device demonstrated improved electrical performance in terms of threshold variation, on/off ratio, subthreshold swing, and mobility compared to the non-annealed reference device. Capacitance-voltage measurement confirmed that annealing can lead to enhanced capacitance properties due to reduced charge trapping. Depth profile analysis using X-ray photoelectron spectroscopy proved that percentage of both the oxygen vacancy (VO) and the hydroxyl groups (M-OH) within the IGZO/Al2O3 layers, which serve as a charge trapping source, can be substantially reduced by annealing the fabricated transistor device. Furthermore, the undesired degradation of the contact interface between source/drain electrode and the channel, which mainly concerns VO, can be largely prevented by post-annealing. Thus, the facile annealing process also improves the electrical bias stress stability. This simple post annealing approach provides a strategy for realising better performance and reliability of the solid sol-gel oxide transistor.

Effect of hybrid UV-thermal energy stimuli on inactivation of S. epidermidis and B. subtilis bacterial bioaerosols.

Bioaerosols have become an increasingly important issue due to their harmful effects on human health. As the concern over airborne microorganisms grows, so does the need to develop and study efficient methods of controlling them. In this study, we designed a hybrid system involving ultraviolet (UV) irradiation and thermal energy and investigated its effects on bacterial bioaerosols, followed by a comparison with thermal energy alone and UV irradiation alone. The results show that the hybrid effect caused no variation in the shape of the normalized particle size distributions of S. epidermidis and B. subtilis bioaerosols. However, a physical transport loss of bacterial bioaerosols developed as the temperature inside the glass quartz tube increased. When bacterial bioaerosols were simultaneously exposed to UV irradiation and thermal energy for less than 1.05 s, more than 99% of S. epidermidis bioaerosols were inactivated at 120 °C with exposure to one UV lamp and at 80 °C with exposure to two UV lamps; and 93.5% and 98.5% of B. subtilis bioaerosols were inactivated at 280 °C with exposure to one and two UV lamps, respectively. Moreover, the hybrid UV-thermal stimuli significantly reduced the concentration of ozone, which is a secondary UV-induced pollutant. Our results show that to obtain the same inactivation efficiency, the hybrid UV-thermal stimuli were more efficient than thermal energy alone in terms of energy consumption and produced significantly less ozone than UV irradiation alone. The hybrid stimuli also had higher inactivation efficiency than UV alone. Therefore, these results provide valuable information for the development of new methods for controlling bioaerosols.