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

Abstract

The present work shows that manganese dioxide (β-MnO2) nano films can be applied as a potential candidate for solar energy conversion. β-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 β-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 β-MnO2 nano films. Unraveling the correlated optical properties with the photoresponse characterizations of β-MnO2 nano films opens the avenue to design and fabricate heterojunction photodiodes based on β-MnO2 nano-films. The photoresponsivity, photoconductivity and specific detectivity of fabricated Au/β-MnO2/p-Si/Al photodiodes were studied.