Evaluation of band offset at amorphous-Si/BaSi{sub 2} interfaces by hard x-ray photoelectron spectroscopy

Journal Article · Thu Apr 28 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4947501· OSTI ID:22594660

Takabe, Ryota; Takeuchi, Hiroki; Du, Weijie; Toko, Kaoru; Suemasu, Takashi ^[1]; Ito, Keita ^[1]; Ueda, Shigenori ^[2]; Kimura, Akio ^[3]

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1. Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)
2. Synchrotron X-Ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan)
3. Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan)

The 730 nm-thick undoped BaSi{sub 2} films capped with 5 nm-thick amorphous Si (a-Si) intended for solar cell applications were grown on Si(111) by molecular beam epitaxy. The valence band (VB) offset at the interface between the BaSi{sub 2} and the a-Si was measured by hard x-ray photoelectron spectroscopy to understand the carrier transport properties by the determination of the band offset at this heterointerface. We performed the depth-analysis by varying the take-off angle of photoelectrons as 15°, 30°, and 90° with respect to the sample surface to obtain the VB spectra of the BaSi{sub 2} and the a-Si separately. It was found that the barrier height of the a-Si for holes in the BaSi{sub 2} is approximately −0.2 eV, whereas the barrier height for electrons is approximately 0.6 eV. This result means that the holes generated in the BaSi{sub 2} layer under solar radiation could be selectively extracted through the a-Si/BaSi{sub 2} interface, promoting the carrier separation in the BaSi{sub 2} layer. We therefore conclude that the a-Si/BaSi{sub 2} interface is beneficial for BaSi{sub 2} solar cells.

• OSTI ID: 22594660
• Journal Information: Journal of Applied Physics, Vol. 119, Issue 16; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM COMPOUNDS
CARRIERS
ELECTRONS
FILMS
HARD X RADIATION
HOLES
INTERFACES
LAYERS
MOLECULAR BEAM EPITAXY
MOLECULAR BEAMS
SILICON
SOLAR CELLS
SOLAR RADIATION
SPECTRA
SURFACES
TRANSPORT THEORY
X-RAY PHOTOELECTRON SPECTROSCOPY