Berlin 2018 – scientific programme

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O: Fachverband Oberflächenphysik

O 33: Semiconductor substrates: Structure, epitaxy and growth

O 33.5: Talk

Tuesday, March 13, 2018, 15:00–15:15, MA 005

In situ study of AlxGa1-xP nucleation on As-modified Si(100) 2° surfaces — •Manali Nandy, Agnieszka Paszuk, Anja Dobrich, Oliver Supplie, Peter Kleinschmidt, and Thomas Hannappel — TU Ilmenau, Gustav-Kirchhoff-Straße 5, 98693 Ilmenau

Epitaxial growth of III-V materials on Si substrates is promising for cost-effective, tandem solar cells with high photovoltaic conversion efficiency. In order to avoid antiphase domains during polar-on-non polar heteroepitaxy, an atomically ordered, As-modified double layer (DL) stepped Si(100)2° surface is employed here for further low-defect III-V growth. After the Si surface preparation, a common approach is to subsequently grow a thin GaP nucleation layer, since this material is almost lattice matched to Si[1]. Here we apply AlxGa1-xP nucleation layer instead of established GaP-on-Si nucleation in order to further modify the atomic and electronic structure of the heterointerface as well as to yield adequate nucleation conditions. Prior to the nucleation, the Si(100)2° surface is exposed to TBAs in an Al-containing III-V MOVPE reactor. We observe that the oxide removal of the Si substrate by HF pre-treatment lowers the maximum process temperature below 820°C[2]. Subsequently the pulsed AlxGa1-xP nucleation layer consisting of Al, Ga, and P pulses is grown at 420°C, followed by a GaP epilayer growth at 600°C. The RAS signal of the grown GaP is benchmarked by low energy electron diffraction(LEED) and the surface morphology is studied by atomic force microscopy(AFM).[1]O. Supplie et al.,APL Mater.3(2015)126110.[2]A. Paszuk,...M. Nandy et al.,Sol. Energ. Mat. Sol. Cells,in press(2017),doi:10.1016/j.solmat.2017.07.032.