The solar response ability and low-cost fabrication of the photoanode are important factors for the effective output of the photoelectrochemical system. Modification of the photoanode by which its ability to absorb irradiation can be manipulated has gained tremendous attention. Here, we demonstrated the MoSe 2 , WSe 2 , and MoSe 2 /WSe 2 nanocrystal thin films prepared by the liquid-phase exfoliated and electrophoresis methods. Atomic force microscopy and high-resolution transmission electron microscopy show that the liquid exfoliated nanocrystals have a few layered dimensions with good crystallinity. Scanning electron microscopy demonstrated uniform distribution and randomly oriented nanocrystals, having a homogeneous shape and size. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectra confirm the equal contribution of MoSe 2 and WSe 2 nanocrystals in the formation of the MoSe 2 /WSe 2 heterojunction. Because of superior absorption of MoSe 2 /WSe 2 heterojunction in the visible region and type-II heterojunction band alignment, in situ measurement of heterojunction electrode shows almost 1.5 times incident photo-to-current conversion efficiency and photoresponsivity in comparison to individual material electrodes. Our result clearly indicates the influence of heterojunction formation between liquid exfoliated nanocrystals on effective separation of photogenerated exciton and enhances charge carrier transfer, which leads to the improvement in photoelectrochemical performance. Liquid exfoliated nanosheet-based heterojunction is attractive as efficient photoanodes for the photoelectrochemical systems.

A diffusion barrier layer of a few nanometers in thickness is required for a Cu/SiO 2 interconnect structure for advanced integrated circuits (ICs). This paper reports a new barrier material and process by chemical vapor deposition (CVD) of a Mn oxide layer using a bis(ethylcyclopentadienyl)manganese precursor. A good adhesion was obtained when the MnO x layer was deposited below 300 • C because of the small amount of carbon inclusion within the layer. The metal-oxide-semiconductor samples of Cu/MnO x /SiO 2 /p-Si showed a very low leakage current of less than 10 −7 A/cm 2 at 4 MV/cm and a negligible shift of the flat-band voltage after thermal annealing and bias temperature annealing. The obtained results indicated that the CVD-deposited MnO x is an excellent diffusion barrier layer for advanced ICs.Index Terms-Chemical vapor deposition (CVD), diffusion barrier, interconnect, manganese oxide, metal-oxide-semiconductor (MOS) capacitors.

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