Bulletin of the American Physical Society
APS March Meeting 2018
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session G60: Poster Session I
Tuesday, March 6, 2018
LACC Room: West Hall A
Abstract: G60.00307 : Energy Band Alignment of ZnSxSe1-x Films on Si for Photovoltaic Carrier-Selective Contacts*
(Applied Physics and Material Science, Caltech)
ZnSxSe1-x films are promising materials for front carrier-selective contacts in silicon photovoltaics given their wide bandgaps and low resistivities compared to amorphous silicon. X-ray photoelectron spectra of ZnSxSe1-x films (x ranging from 0 to 1) grown on Si by molecular beam epitaxy were used to measure the conduction band and valence band offsets of ZnSxSe1-x with respect to Si for purposes of accurate optoelectronic simulations of photovoltaic devices incorporating ZnSxSe1-x carrier-selective contacts. Conduction band offsets ranged from 0.42 eV (x = 1) to 1.52 eV (x = 0) showing a significant departure from both Anderson model and density functional theory predictions. These offsets represent transmission probabilities through the ZnSxSe1-x depletion region of 94%–0% for an electron in the bulk silicon conduction band, suggesting Se-rich ZnSxSe1-x films will be necessary for effective ZnSxSe1-x electron-selective contacts on Si. The open-circuit voltage, fill factor, and conversion efficiency of ZnSxSe1-x/Si cells will be discussed.
*This material is based upon work supported by the NSF and the DOE under NSF CA No. EEC-1041895, by the DOE under Award Nos. DE-EE0006335 and DE-EE0004946, and by the NSF Graduate Research Fellowship under Grant No. 1144469.
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