  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%.
