Diluted ZnMnTe oxide : A multi-band semiconductor for high efficiency solar cells

Using oxygen ion implantation and pulsed laser melting, we have synthesized thin films of highly mismatched ternary (y = 0) and quaternary (y = 0.12) Zn_1-yMn_yO_xTe_1-x alloys with oxygen content in excess of x ∼ 0.01. We show that incorporation of a small amount of isoelectronic oxygen leads to the formation of a narrow, oxygen-derived band of extended states located well below the conduction band edge of the Zn_1-yMn_yTe matrix. The structure of the conduction band is well described by the anticrossing interaction between O localized states and the extended states of the host semiconductor matrix. As a result the conduction band splits into two subbands with distinctly non-parabolic dispersion relations. The three absorption edges of this material (∼0.73, 1.83 and 2.56 eV) cover the entire solar spectrum providing a material envisioned for the multi-band, single junction, high efficiency photovoltaic devices. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.