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In the current work, CuO thin films (~ 110 nm) are grown by employing chemical bath deposition (CBD) method on Si substrate for fabricating the p-CuO/n-Si heterojunction photodetectors. The as-grown films are annealed at 250, 550 and 850 °C for 10 min in Ar ambient for tuning optoelectronic properties of the as-grown CuO thin films. Comparative study on systematic annealing of the film within 250-550 °C indicates a morphological change of the as-grown CuO film to nano-fiber type with its chemical composition remaining unchanged. A variation of refractive index and dielectric constant in the range of 2.65-2.93 and 7.2-9.7, and a change of absorption coefficient and bandgap from 1.33 × 105 to 6.06 × 105 cm− 1 and 1.5 to 2.16 eV have been observed. The current-voltage characteristics both in dark and illuminated conditions suggest that the annealing of CuO film at 550 °C provides the best performance in terms of photo-to-dark current ratio and photoresponsivity. A respective enhancement of 5.07 and 10% for the photo-to-dark ratio and photoresponsivity has been observed for the 550 °C annealed sample. [ABSTRACT FROM AUTHOR]

Thin film of p-type cupric oxide ( p -CuO) is grown on silicon (n-Si) substrate by using chemical bath deposition (CBD) technique and a precise control of thickness from 60 nm to 178 nm has been achieved. The structural properties and stoichiometric composition of the grown films are observed to depend significantly on the growth time. The chemical composition, optical properties, and structural quality are investigated in detail by employing XRD, ellipsometric measurements and SEM images. Also, the elemental composition and the oxidation states of Cu and O in the grown samples have been studied in detail by XPS measurements. Thin film of 110 nm thicknesses exhibited the best performance in terms of crystal quality, refractive index, dielectric constant, band-gap, and optical properties. The study suggests synthesis route for developing high quality CuO thin film using CBD method for electronic and optical applications. [ABSTRACT FROM AUTHOR]

In this work, the authors report a comparative study on the physical and electrical properties of n-ZnO nanowires (NWs)/p-Si and n-ZnO NWs/p-CuO film heterojunctions by employing chemical bath deposition method. Solar energy conversion efficiency of the n-ZnO NWs/p-CuO and n-ZnO NWs/p-Si heterojunctions is obtained to be 3.92% and 0.008%, respectively, under 100 mW/cm 2 input incident power. Thus, the n-ZnO NWs/p-CuO heterojunctions exhibit superior photovoltaic performance in comparison to the n-ZnO NWs/p-Si system. [ABSTRACT FROM AUTHOR]

In this work, the CuO nano-powder has been synthesized by employing chemical bath deposition technique for its subsequent use to grow ultrathin film (20 nm) of p-CuO on n-Si substrate for the fabrication of p-CuO/n-Si hetero-junction diodes. The thin CuO film has been grown by employing vapour-liquid-solid method. The crystalline structure and chemical phase of the film are characterized by employing field-emission scanning electron microscopy and X-ray diffraction studies. Chemical stoichiometry of the film has been confirmed by using energy dispersive X-ray spectroscopy. The potential for photovoltaic applications of such films is investigated by measuring the junction current-voltage characteristics and by extracting the relevant parameters such as open circuit photo-generated voltage, short circuit current density, fill-factor and energy conversion efficiency. [ABSTRACT FROM AUTHOR]

• Growth of CuO film and ZnO nanowires by employing CBD method. • Potential of ZnO nanowires for improving power conversion efficiency. • Improvement of photovoltaic parametrices of p-CuO/n-ZnO NWs heterojunction. • Achievement of a significantly high solar energy conversion efficiency of 4.19%. P-type cupric oxide (p-CuO) and p-type cupric-oxide/n-type zinc oxide nanowires (p-CuO/n-ZnO NWs) heterojunction diodes were fabricated by employing chemical bath deposition technique on n-silicon (n-Si) substrate. The work demonstrates the potential of zinc oxide nanowires as window layer owing to its wide and direct band gap for metal oxide based solar cells. Optical and electronic properties of the CuO film and ZnO nanowires including refractive index, absorption coefficient and band gaps were investigated by using spectroscopic ellipsometric analysis. Impact of nanowire morphology, chemical composition and crystallite structures on optical and photovoltaic performance of p-CuO/n-Si and p-CuO/n-ZnO NWs were investigated. Absorption coefficient in the near UV–visible range was observed to improve significantly by incorporating n-ZnO nanowires which was desired for the solar cell applications. The comparative photovoltaic performance showed improvements of both the short-circuit current density (J sc) and open circuit voltage (V oc), due to reduced interface recombination and enhanced absorption for the increased surface-to-volume ratio of ZnO nanowires in the p-CuO/n-ZnO NWs heterojunction. Photovoltaic performance with J sc , V oc and power conversion efficiency of 11.1 mA/cm2, 1.1 V and 4.19% was obtained. Therefore, the work emphasizes importance of using the combination of n-ZnO nanowires and p-CuO film as the wide- and low- band gap materials for improving performance of the future low-cost solar cell with superior efficiency. [ABSTRACT FROM AUTHOR]

In the current work, a single crystalline β-Gallium Oxide (Ga 2 O 3) thin film (~15 nm) is grown on Si-substrate by employing catalyst-modified vapor-liquid-solid (VLS) method. The FESEM and AFM images indicate the formation of a continuous film with small surface roughness. XRD measurement confirms the formation of a highly crystalline < 1 ¯ 11 >-plane of β-phase of Ga 2 O 3. The chemical states and optical properties of such films are analyzed by X-ray photoelectron spectroscopy (XPS) and Spectroscopic ellipsometry (SE). The energy bandgap, refractive index and extinction coefficient of the grown β-Ga 2 O 3 film are obtained to be 4.78 eV, 1.84 and 0.10, respectively. The vacancies/defect states are studied from Photoluminescence (PL) spectra where the major PL-peaks corroborate with the transitional energy values obtained from SE measurement. Therefore, the study suggests that the VLS method, amongst the state-of-the-art growth techniques, is capable of growing high-quality single crystalline β-Ga 2 O 3 thin film in a relatively simple and cost-effective approach. Image 1061 • Growth of β-Ga 2 O 3 film is reported, for the first time, by employing VLS technique. • The Au catalyst is modified to provide ambient condition for rapid growth of the film. • Single crystalline film (~15 nm) is achieved by adopting such catalyst modified method. [ABSTRACT FROM AUTHOR]