We report the realization of a new multi-band-gap semiconductor. The highly mismatched alloy Zn 1-y Mn y O x Te 1-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 Zn 1-y Mn y Te host. When only 1.3% of Te atoms is replaced with oxygen in a Zn 0.88 Mn 0.12 Te 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 oxygenderived band and the conduction band are considered. With multiple band gaps that fall within the solar energy spectrum, Zn 1-y Mn y O x Te 1-x is a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.PACS numbers: 71.20.Nr; 78.66.Hf; 61.72.Vv; 89.30.Cc The unusual properties of HMAs are well explained by the recently developed band anticrossing (BAC) model [3][4][5]. The model has also predicted several new effects that were later confirmed by experiments [6][7][8]. According to this model the electronic structure of the HMAs is determined by the interaction between localized states associated with N or O atoms 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 [3].In most instances, e.g. N in GaAs or O in CdTe, the localized states are located within the conduction band and the anticrossing interaction results in the formation of a relatively wide lower subband [5]. The subband is shifted to lower energies leading to a reduction of the energy band gap. The BAC model predicts that a narrow band can be formed only if the localized states occur well below the conduction band edge. Such a case is realized in ZnTe, MnTe and Zn 1-y Mn y Te alloys where the O level is located roughly 0.2 eV below the conduction band edge.We have shown recently that pulsed laser melting (PLM) followed by rapid thermal annealing (RTA) is well suited for the synthesis of HMAs. The combined ion 3 beam and laser processing approach has been demonstrated as an effective approach to synthesize dilute semiconductor alloys including GaN x As 1-x [9,10] and Ga 1-x Mn x As [11].Large enhancement by a factor of five in the incorporation of N in N + -implanted GaAs was observed. This is attributed to the rapid recrystallization rate associated with this process which results in the incorporation of impurity atoms to a level well above the solubility limit [12,13].Here we report the design and synthesis of a new type of material, the highly semiconductor [20,21]. Even for this non-optimal band gap configuration we calculate a power conversion efficiency of 45%, which is higher than th...

We demonstrate a monolithic waveguide sensor integrated with a detector on-chip for mid-infrared absorption spectroscopic sensing. The optical sensing element comprises a chalcogenide glass spiral waveguide, and the detector is a PbTe photoconductor integrated directly with the chalcogenide waveguide. The limit of detection of the sensor for methane gas was experimentally assessed to be 1% by volume. Further optimization of the fabrication process and normalization of the laser power fluctuations should result in a maximum sensitivity of 330 ppmv.

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