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We fabricated AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) on Si substrates with RF-sputtered HfO 2 as a gate insulator. We obtained a high breakdown voltage of 1524 V and a high on/off current ratio of 2.37 × 10 10 in the MOS-HEMT with a 15 nm-thick RF-sputtered HfO 2 while a conventional HEMT had 470 V and 7.61 × 10 3 . The MOS-HEMT with the HfO 2 showed a gate leakage current of −67 pA mm −1 at V GS = −10 V and V DS = 100 V and the drain leakage current was not considerably altered for 100 s. However, the conventional HEMT without a gate insulator had a large gate leakage current of −44.7 μA mm −1 and the drain leakage current was increased from 57.5 to 496 μA mm −1 for 100 s. We have also evaluated the blocking characteristics and passivation effects of HfO 2 by measuring various electrical properties such as pulsed I-V and the surface leakage current at a mesa-isolated two-ohmic pad before and after HfO 2 sputtering.

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In this study, we have deposited organic-inorganic hybrid semiconducting hydroquinone (HQ)/zinc oxide (ZnO) superlattices using molecular-atomic layer deposition, which enables accurate control of film thickness, excellent uniformity, and sharp interfaces at a low deposition temperature (150 C). Self-limiting growth of organic layers is observed for the HQ precursor on ZnO surface. Nano-laminates were prepared by varying the number of HQ to ZnO cycles in order to investigate the physical and electrical effects of different HQ to ZnO ratios. It is indicated that the addition of HQ layer results in enhanced mobility and reduced carrier concentration. The highest Hall mobility of approximately 2.3 cm 2 /VÁs and the lowest n-type carrier concentration of approximately 1.0 Â 10 18 /cm 3 were achieved with the organic-inorganic superlattice deposited with a ratio of 10 ZnO cycles to 1 HQ cycle. This study offers an approach to tune the electrical transport characteristics of ALD ZnO matrix thin films using an organic dopant. Moreover, with organic embedment, this nano-laminate material may be useful for flexible electronics. V

A non-polar solvent secondary washing process employing a CBZ + PCBM hybrid solution is suggested during perovskite spin coating. This approach could offer a very uniform topography of the surfaces which contributes to the construction of planar-type perovskite solar cells with enhanced power conversion efficiencies.