Bosco, Jeffrey P. and Demers, Steven B. and Kimball, Gregory M. and Lewis, Nathan S. and Atwater, Harry A. (2012) Band alignment of epitaxial ZnS/Zn_(3)P_2 heterojunctions. Journal of Applied Physics, 112 (9). Art. No. 093703 . ISSN 0021-8979. doi:10.1063/1.4759280. https://resolver.caltech.edu/CaltechAUTHORS:20130110-104540834
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Abstract
The energy-band alignment of epitaxial zb-ZnS(001)/α-Zn_(3)P_(2)(001) heterojunctions has been determined by measurement of shifts in the phosphorus 2p and sulfur 2p core-level binding energies for various thicknesses (0.6–2.2 nm) of ZnS grown by molecular beam epitaxy on Zn_(3)P_(2). In addition, the position of the valence-band maximum for bulk ZnS and Zn3P2 films was estimated using density functional theory calculations of the valence-band density-of-states. The heterojunction was observed to be type I, with a valence-band offset, ΔE_V, of −1.19 ± 0.07 eV, which is significantly different from the type II alignment based on electron affinities that is predicted by Anderson theory. n^(+)-ZnS/p-Zn_(3)P_(2) heterojunctions demonstrated open-circuit voltages of >750 mV, indicating passivation of the Zn_(3)P_(2) surface due to the introduction of the ZnS overlayer. Carrier transport across the heterojunction devices was inhibited by the large conduction-band offset, which resulted in short-circuit current densities of <0.1 mA cm^(−2) under 1 Sun simulated illumination. Hence, constraints on the current density will likely limit the direct application of the ZnS/Zn_(3)P_(2) heterojunction to photovoltaics, whereas metal-insulator-semiconductor structures that utilize an intrinsic ZnS insulating layer appear promising.
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| Additional Information: | © 2012 American Institute of Physics. Received 10 September 2012; accepted 25 September 2012; published online 2 November 2012. This work was supported by the Dow Chemical Company and by the Department of Energy, Office of Basic Energy Sciences under Grant No. DE-FG02-03ER15483. The authors would like to thank Joseph Beardslee for his assistance with the Kratos XPS measurements. J.P.B. acknowledges the NSF for a graduate research fellowship. | |||||||||
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| Subject Keywords: | binding energy; current density; density functional theory; electronic density of states; II-VI semiconductors; MIS structures; molecular beam epitaxial growth; semiconductor epitaxial layers; valence bands; wide band gap semiconductors; zinc compounds | |||||||||
| Issue or Number: | 9 | |||||||||
| Classification Code: | PACS: 73.40.Qv; 71.20.Nr; 71.15.Mb; 81.15.Hi | |||||||||
| DOI: | 10.1063/1.4759280 | |||||||||
| Record Number: | CaltechAUTHORS:20130110-104540834 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20130110-104540834 | |||||||||
| Official Citation: | Band alignment of epitaxial ZnS/Zn[sub 3]P[sub 2] heterojunctions Jeffrey P. Bosco, Steven B. Demers, Gregory M. Kimball, Nathan S. Lewis, and Harry A. Atwater, J. Appl. Phys. 112, 093703 (2012), DOI:10.1063/1.4759280 | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 36298 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | INVALID USER | |||||||||
| Deposited On: | 10 Jan 2013 21:52 | |||||||||
| Last Modified: | 09 Nov 2021 23:21 |
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