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Diluted II-VI Oxide Semiconductors with Multiple Band Gaps

K. M. Yu·W. Walukiewicz·J. Wu·W. Shan·J. W. Beeman·M. A. Scarpulla·O. D. Dubon·P. Becla
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Abstract

We report the realization of a new multi-band-gap semiconductor. The highly mismatched alloy Zn1-yMnyOxTe1-x has been synthesized using the combination of oxygen ion implantation and pulsed laser melting. Incorporation of small quantities of isovalent oxygen leads to the formation of a narrow, oxygen-derived band of extended states located within the band gap of the Zn1-yMnyTe host. When only 1.3% of Te atoms is replaced with oxygen in a Zn0.88Mn0.12Te crystal (with band gap of 2.32 eV) the resulting band structure consists of two direct band gaps with interband transitions at ~1.77 eV and 2.7 eV. This remarkable modification of the band structure is well described by the band anticrossing model in which the interactions between the oxygen-derived band and the conduction band are considered. With multiple band gaps that fall within the solar energy spectrum, Zn1-yMnyOxTe1-x is a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.

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K. M. Yu, W. Walukiewicz, J. Wu, W. Shan, J. W. Beeman, M. A. Scarpulla, O. D. Dubon, P. Becla. 2003-09-20. Diluted II-VI Oxide Semiconductors with Multiple Band Gaps. https://doi.org/10.1103/physrevlett.91.246403

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