Energy band alignment at Cu2O/ZnO heterojunctions characterized by in situ x-ray photoelectron spectroscopy

doi:10.1088/1674-1056/28/8/087301

Abstract With the increasing interest in Cu₂O-based devices for photovoltaic applications, the energy band alignment at the Cu₂O/ZnO heterojunction has received more and more attention. In this work, a high-quality Cu₂O/ZnO heterojunction is fabricated on a c-Al₂O₃ substrate by laser-molecular beam epitaxy, and the energy band alignment is determined by x-ray photoelectron spectroscopy. The valence band of ZnO is found to be 1.97 eV below that of Cu₂O. A type-Ⅱ band alignment exists at the Cu₂O/ZnO heterojunction with a resulting conduction band offset of 0.77 eV, which is especially favorable for enhancing the efficiency of Cu₂O/ZnO solar cells.

Keywords: Cu₂O ZnO x-ray photoelectron spectroscopy laser-molecular beam epitaxy

Received: 25 November 2018
Revised: 06 May 2019
Published: 05 August 2019

PACS:	73.40.Lq	(Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions)
	82.80.Pv	(Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.))
	77.55.hf	(ZnO)
	73.20.At	(Surface states, band structure, electron density of states)

Fund: Project supported by the National Natural Science Foundation of China (Grant No. 11404302) and the Laser Fusion Research Center Funds for Young Talents, China (Grant No. RCFPD1-2017-9).

Corresponding Authors: Wei-Dong Wu
E-mail: wuweidongding@163.com

Cite this article:

Yan Zhao(赵妍), Hong-Bu Yin(尹泓卜), Ya-Jun Fu(符亚军), Xue-Min Wang(王雪敏), Wei-Dong Wu(吴卫东) Energy band alignment at Cu₂O/ZnO heterojunctions characterized by in situ x-ray photoelectron spectroscopy 2019 Chin. Phys. B 28 087301

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