ABSTRACT:The relationships between the properties and structure are discussed for poly(vinyl alcohol)(PVA)/silica composites prepared through the sol-gel process. The composites became stiff and brittle with increasing the silica content. The properties of the composites were changed drastically at around the composition of PVA/silica ϭ 70/30 wt %. For example, there was no large change in the Young's modulus above 30 wt % of silica content (Pure PVA: 31.8 MPa, silica 30%: 52.6 MPa, silica 50%: 55.2 MPa). Consequently, it was considered that the three-dimensional network structure of silica could be formed in the composite with more than 30 wt % of silica in PVA. From this behavior, it could be considered that the crystal growth of PVA was remarkably inhibited by silica network.

Single-crystalline silicon (sc-Si) complementary metal-oxide-semiconductor (CMOS) circuits were fabricated on a polyethylene terephthalate (PET) substrate using meniscus force-mediated layer transfer. The introduction of a two-step tapered SiO 2 structure formed using low-dose and high-energy pillar shaping ion implantation (I/I) and self-limited SiO 2 pillar etching were crucial for obtaining a high transfer yield of 99.86% and simultaneous transfer of both n-and p-channel sc-Si islands to the PET substrate. The fabricated MOS field-effect transistors exhibited a high field effect mobility of 603 cm 2 V −1 s −1 (n) and 172 cm 2 V −1 s −1 (p), respectively. The CMOS inverters exhibited clear input/output characteristics under a supply voltage of 2.0 V, and high-speed operation of a five-stage ring oscillator (RO) with an operating frequency of 14.6 MHz was realized. Moreover, the oscillation frequency of the RO transferred onto the PET was 3.5 times that of the non-transferred RO owing to the reduction in the parasitic capacitance.INDEX TERMS CMOS integrated circuits, CMOS process, flexible electronics, single-crystalline silicon layer transfer.