Preparation and optical characterization of β-MnO2 nano thin films for application in heterojunction photodiodes

The present work shows that manganese dioxide (beta-MnO2) nano films can be applied as a potential candidate for solar energy conversion. beta-MnO2 nano thin films were successfully grown on glass and quartz substrates using thermal evaporation technique. The structural properties of as-deposited and annealed thin films were analyzed using both X-ray diffraction and field emission scanning electron microscopy techniques. The spectroscopic characterizations of beta-MnO2 nano thin films with different film thickness were studied using spectrophotometric technique in the wavelength of 200-2400 nm. The optical constants of these films were calculated and showed variation with film thickness and annealing temperature. Wemple -DiDomenico oscillator model was applied in the non-absorbing region of refractive index spectrum in order to evaluate the dispersion parameters. The nonlinear optical parameters were calculated using the linear optical parameters. The annealing temperature considered to be a good tool for enhancement of the nonlinear optical parameters of beta-MnO2 nano films. Unraveling the correlated optical properties with the photoresponse characterizations of beta-MnO2 nano films opens the avenue to design and fabricate heterojunction photodiodes based on beta-MnO2 nano-films. The photoresponsivity, photoconductivity and specific detectivity of fabricated Au/beta-MnO2/p-Si/Al photodiodes were studied. (C) 2018 Elsevier B.V. All rights reserved.