|Title||Variations of ionization potential and electron affinity as a function of surface orientation: The case of orthorhombic SnS|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Stevanović, V, Hartman, K, Jaramillo, R, Ramanathan, S, Buonassisi, T, Graf, P|
|Journal||Applied Physics Letters|
|ISBN Number||0003-6951, 1077-3118|
|Keywords||Annealing, Atomic Force Microscopy, Chalcogenides, Density Functional Theory, Electronic Structure, Grain Boundaries, Interface Structure, Kelvin Probe, Scanning Probe Microscopy, Thermal/E-Beam Evaporation, Thin Films, Tin Chalcogenides, Work Function, X-Ray Scattering|
We investigated the dependence of absolute SnS band-edge energies on surface orientation using density functional theory and GW method for all surfaces with Miller indices − 3 ≤ h , k , l ≤ 3 and found variations as large as 0.9 eV as a function of (hkl). Variations of this magnitude may affect significantly the performance of photovoltaic devices based on polycrystalline SnS thin-films and, in particular, may contribute to the relatively low measured open circuit voltage of SnS solar cells. X-ray diffraction measurements confirm that our thermally evaporated SnS films exhibit a wide distribution of different grain orientations, and the results of Kelvin force microscopy support the theoretically predicted variations of the absolute band-edge energies.