Dresden 2017 – wissenschaftliches Programm
HL 8.8: Vortrag
Montag, 20. März 2017, 11:30–11:45, POT 251
Many-body effects in X-ray absorption spectra of the sulfur L2,3 edge in Cu2ZnSnS4 — •Archana Manoharan1, Lorenzo Pardini1, and Claudia Draxl1,2 — 1Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Germany — 2European Theoretical Spectroscopic Facility (ETSF)
The kesterite material Cu2ZnSnS4 (CZTS) is a promising candidate as an absorber layer for solar-cell applications. In the present work, we study its structural, electronic, and X-ray absorption properties using a first-principles approach. We explore the X-ray absorption spectra at the sulfur L2,3 edge in CZTS by solving the Bethe-Salpeter equation (BSE) and compare them to corresponding binary phases, i.e., ZnS and SnS2. Special emphasis is put on the spin-orbit coupling between the S 2p1/2 and 2p3/2 core states. In comparison to the independent-particle approximation, the inclusion of Coulomb interaction redshifts the absorption edge in all three materials. In case of CZTS, a bound exciton is found. It is formed by transition from the S 2p3/2 core state. The second peak with excitonic character is due to the mixing of excitation channels of the L2 and L3 edges. In the binary phases, a bound state is observed in SnS2 but not in ZnS. We assign the bound exciton in CZTS to hybridisation of Sn with S. The calculated BSE results are in good agreement with experimental spectra.