First-principles study on oxidation of Ge and its interface electronic structures

Abstract

We review a series of first-principles studies on the defect generation mechanism and electronic structures of the Ge/GeO 2 interface. Several experimental and theoretical studies proved that Si atoms at the Si/SiO 2 interface are emitted to release interface stress. In contrast, total-energy calculation reveals that Ge atoms at the Ge/GeO 2 interface are hardly emitted, resulting in the low trap density. Even if defects are generated, those at the Ge/GeO 2 interface are found to behave differently from those at the Si/SiO 2 interface. The states attributed to the dangling bonds at the Ge/GeO 2 interface lie below the valence-band maximum of Ge, while those at the Si/SiO 2 interface generate the defect state within the band gap of Si. First-principles electron-transport calculation elucidates that this characteristic behavior of the defect states is relevant to the difference in the leakage current through the Si/SiO 2 and Ge/GeO 2 interfaces.

Growth of small GeO2 single crystals on a polyvinyl chloride substrate at room temperature using oversaturate aqueous solution

“…As compared to silicon dioxide, germanium dioxide has higher permittivity and more than twice as high piezoelectric constant, while these properties remain up to about 1273 K; in addition, germanium dioxide is reported to feature excellent electrical characteristics as a variable resistance memory . For this reason, germanium is now being reconsidered as a next‐generation material for electronic devices, while chemical characteristics and usage of germanium dioxide are gaining importance in design of advanced electronic devices . Germanium dioxide can take crystal structure of α‐quartz type or cristobalite type, while likely taking amorphous form; though it resembles silicon dioxide, a number of distinctions are known including water solubility and organic polymerization catalytic activity .…”

“…3 For this reason, germanium is now being reconsidered as a next-generation material for electronic devices, while chemical characteristics and usage of germanium dioxide are gaining importance in design of advanced electronic devices. 4 Germanium dioxide can take crystal structure ofquartz type or cristobalite type, while likely taking amorphous form; though it resembles silicon dioxide, a number of distinctions are known including water solubility and organic polymerization catalytic activity. [5][6][7] Germanium dioxide is reported to be water soluble but the solubility value is estimated differently.…”