Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 33: Semiconductor substrates: Structure, epitaxy and growth

O 33.2: Vortrag

Dienstag, 13. März 2018, 14:15–14:30, MA 005

Study of As-modified Si(100) surfaces for III-V-on-Si heteroepitaxy in CVD ambient — •Agnieszka Paszuk, Oliver Supplie, Manali Nandy, Anja Dobrich, Peter Kleinschmidt, and Thomas Hannappel — Institute of Physics, Technische Universität Ilmenau, Germany

III-V heteroepitaxy on Si(100) holds promise for low cost, high-efficiency optoelectronic devices. In polar-on-nonpolar epitaxy, it is crucial to prepare Si(100) surfaces with double-layer (DL) steps in order to avoid antiphase domains, which can significantly reduce the efficiency of the device. Here, we employ vicinal and almost exactly oriented Si(100) substrates relevant for photovoltaic and CMOS applications, respectively. We study the interaction of Si(100) surfaces with Arsenic, which is present in most application-relevant III-V MOCVD reactors, supplied either directly via the TBAs precursor or indirectly as background As_x. The entire process is controlled in situ by reflectance anisotropy spectroscopy (RAS) and the obtained spectra are benchmarked by UHV surface analytic techniques. We show that specific processing routes enable control of the dimer orientation on Si(100):As surfaces and we demonstrate low-offcut single-domain Si(100):As surfaces with regular, true DL steps. The process conditions to obtain a DL stepped surface depend on the offcut magnitude. We found that both As coverage and dimer orientation on the Si surface contribute to the RA spectral line-shape, which opens perspectives to fine-tune the surface structure as desired for further III-V growth.