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arXiv · 1801.05480

Characterization of free standing InAs quantum membranes by standing wave hard x-ray photoemission spectroscopy

G. Conti·S. Nemšák·C. -T. Kuo·M. Gehlmann·C. Conlon·A. Keqi·A. Rattanachata·O. Karslıoğlu·J. Mueller·J. Sethian·H. Bluhm·J. E. Rault·J. P. Rueff·H. Fang·A. Javey·C. S. Fadley
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Abstract

Free-standing nanoribbons of InAs quantum membranes (QMs) transferred onto a (Si/Mo) multilayer mirror substrate are characterized by hard x-ray photoemission spectroscopy (HXPS), and by standing-wave HXPS (SW-HXPS). Information on the chemical composition and on the chemical states of the elements within the nanoribbons was obtained by HXPS and on the quantitative depth profiles by SW-HXPS. By comparing the experimental SW-HXPS rocking curves to x-ray optical calculations, the chemical depth profile of the InAs(QM) and its interfaces were quantitatively derived with angstrom precision. We determined that: i) the exposure to air induced the formation of an InAsO$_4$ layer on top of the stoichiometric InAs(QM); ii) the top interface between the air-side InAsO$_4$ and the InAs(QM) is not sharp, indicating that interdiffusion occurs between these two layers; iii) the bottom interface between the InAs(QM) and the native oxide SiO$_2$ on top of the (Si/Mo) substrate is abrupt. In addition, the valence band offset (VBO) between the InAs(QM) and the SiO$_2$/(Si/Mo) substrate was determined by HXPS. The value of $VBO = 0.2 \pm 0.04$ eV is in good agreement with literature results obtained by electrical characterization, giving a clear indication of the formation of a well-defined and abrupt InAs/SiO$_2$ heterojunction. We have demonstrated that HXPS and SW-HXPS are non-destructive, powerful methods for characterizing interfaces and for providing chemical depth profiles of nanostructures, quantum membranes, and 2D layered materials.

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G. Conti, S. Nemšák, C. -T. Kuo, M. Gehlmann, C. Conlon, A. Keqi, A. Rattanachata, O. Karslıoğlu, J. Mueller, J. Sethian, H. Bluhm, J. E. Rault, J. P. Rueff, H. Fang, A. Javey, C. S. Fadley. 2018-01-16. Characterization of free standing InAs quantum membranes by standing wave hard x-ray photoemission spectroscopy. https://arxiv.org/abs/1801.05480

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