MHOS (metal-HfO2–SiO2–Si) structure capacitors were fabricated to investigate the charge trapping properties of HfO2 layer with various thicknesses for the applications of charge trap flash (CTF) memory devices. Also, the centroid of charge trap in HfO2 layer was extracted by constant current stress method and compared with that of conventional Si3N4 layer. The gate leakage current of MHOS capacitor due to tunneling was significantly reduced by stacking the HfO2 trap layer on thin SiO2 tunnel layer. The MHOS capacitors showed a larger memory window than the MNOS (metal-Si3N4–SiO2–Si) capacitors at the same trap layer thickness, because the HfO2 layer has better charge trapping efficiency than the Si3N4 layer. It is found that ultrathin HfO2 trap layer with a thickness of 2 nm stored almost the same charges with Si3N4 layer with a thickness of 7 nm. Consequently, the application of ultrathin HfO2 to charge storage layer can considerably improve the performance and enhance the high density of CTF memory.

In this paper, we present the results of the fabrication and characterization of Li2CO3 doped (Ba,Sr)TiO3 ceramics for the low temperature sintering processes. In these days, low temperature sintering process has been widely spread out for the integrated electronic modules for the communication systems such as front-end modules, antenna modules, and switching modules. Generally it is believed that low temperature sintering process can be applied to the functional materials if they can be sintered less than 900 °C. However, BaSrTiO3 materials for the tunable microwave devices applications have relatively high sintering temperature of 1350 °C. Therefore, in this study to obtain low sintering temperature, we have added 1–5 wt % of Li2CO3 to BaSrTiO3 materials to reduce the sintering temperature from 1350 to around 900 °C.

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