Molybdenum disulfide (MoS) has recently emerged as a promising candidate for fabricating ultrathin-film photovoltaic devices. These devices exhibit excellent photovoltaic performance, superior flexibility, and low production cost. Layered MoS deposited on p-Si establishes a built-in electric field at MoS/Si interface that helps in photogenerated carrier separation for photovoltaic operation. We propose an AlO-based passivation at the MoS surface to improve the photovoltaic performance of bulklike MoS/Si solar cells. Interestingly, it was observed that AlO passivation enhances the built-in field by reduction of interface trap density at surface. Our device exhibits an improved power conversion efficiency (PCE) of 5.6%, which to our knowledge is the highest efficiency among all bulklike MoS-based photovoltaic cells. The demonstrated results hold the promise for integration of bulklike MoS films with Si-based electronics to develop highly efficient photovoltaic cells.
In this paper, we report the effect of 1.5 MeV proton beam irradiation dose on the structural and electrical properties of TiO 2 thin films deposited on n-Si substrates. The formation and transformation of different TiO 2 phases in the irradiated thin films were characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). X-ray diffraction measurements revealed that the as grown film was rich in Ti 5 O 9 phase and then converted to mixed phases of TiO 2 (rutile and anatase) after exposure with radiation doses up to 5 Â 10 14 cm À2 . The XPS results revealed the formation of oxygen vacancy (negative) traps in the exposed TiO 2 films, which showed strong dependence on the dose. The C-V measurements showed that proton radiations also damaged the Si substrate and created deep level defects in the substrate, which caused a shift of 0.26 6 0.01 V in the flat band voltage (V FB ). I-V measurements showed that the ideality factor increased and the rectification ratio dropped with the increase in the radiation dose. The present study showed the stability of TiO 2 /Si interface and TiO 2 film as an oxide layer against proton radiations. V C 2014 AIP Publishing LLC. [http://dx.
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