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Heo, Jae Yeong

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Heo

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Jae Yeong

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Heo, Jae Yeong
Author's Publications: search.filters.isAuthorOfPublication.5e50366d-a841-4b72-a0c5-595273d285d7

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    \((Sn,Al)O_x\) Films Grown by Atomic Layer Deposition
    (American Chemical Society, 2011) Heo, Jae Yeong; Liu, Yiqun; Sinsermsuksakul, Prasert; Li, Zhefeng; Sun, Leizhi; Noh, Wontae; Gordon, Roy
    \((Sn,Al)O_x\) composite films with various aluminum (Al) to tin (Sn) ratios were deposited using an atomic layer deposition technique. The chemisorption behavior of cyclic amide of tin(II) and trimethylaluminum were analyzed by Rutherford backscattering spectroscopy. Both precursors showed retarded and enhanced chemisorption on \(Al_2O_3\) and \(SnO_2\) surfaces, respectively. The films show highly anisotropic electrical conductivity, i.e., much higher resistivity in the direction through the film than parallel to the surface of the film. The cause of the anisotropy was investigated by cross-sectional transmission electron microscopy, which showed a nanolaminate structure of crystalline \(SnO_2\) grains separated by thin, amorphous \(Al_2O_3\) monolayers. When the Al concentration was higher than \( \sim 35\) atom percent, the composite films became amorphous, and the vertical and lateral direction resistivity values converged toward one value. By properly choosing the ratio of \(SnO_2\) and \(Al_2O_3\) subcycles, controlled adjustment of film electrical resistivity over more than 15 orders of magnitude was successfully demonstrated.
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    Atomic Layer Deposition of Tin Monosulfide Thin Films
    (Wiley-VCH, 2011) Sinsermsuksakul, Prasert; Heo, Jae Yeong; Noh, Wontae; Hock, Adam S.; Gordon, Roy
    Thin film solar cells made from earth-abundant, non-toxic materials are needed to replace the current technology that uses \(Cu(In,Ga)(S,Se)_2\) and \(CdTe\), which contain scarce and toxic elements. One promising candidate absorber material is tin monosulfide (\(SnS\)). In this report, pure, stoichiometric, single-phase SnS films were obtained by atomic layer deposition (ALD) using the reaction of \(bis(N,N′-diisopropylacetamidinato)tin(II)\) \([Sn(MeC(N-^{i}Pr)_{2})_{2}]\) and hydrogen sulfide \((H_2 S)\) at low temperatures (100 to 200 \(°C\)). The direct optical band gap of SnS is around 1.3 eV and strong optical absorption \((\alpha > 10^4 cm^{−1})\) is observed throughout the visible and near-infrared spectral regions. The films are p-type semiconductors with carrier concentration on the order of \(10^{16} cm^{−3}\) and hole mobility \(0.82–15.3cm^{2}V^{−1}s^{−1}\) in the plane of the films. The electrical properties are anisotropic, with three times higher mobility in the direction through the film, compared to the in-plane direction.
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    Publication
    Low Temperature Atomic Layer Deposition of Tin Dioxide, SnO\(_2\)
    (2010) Heo, Jae Yeong; Hock, Adam S.; Gordon, Roy