Variations of Optical and Structural Properties of CoxOy Thin Films with Thermal Treatment

Abstract

The effects of thermal treatment on the optical and structural properties of cobalt oxide Co O thin films synthesized in the pores of PVP by chemical bath deposition technique were investigated. Films deposited were crystalline. The optical properties of the films were got from absorbance, transmittance reflectance, refractive index, absorption coefficient, and extinction coefficient measurements. The synthesized Co O films turned out to be cobalt oxyhydroxide , CoO(OH), nanocrystals. The crystals obtained were of size 41.84 nm; however, as annealing temperature increased, the size decreased to 16.28 nm. The absorption coefficient, refractive index, and extinction coefficient were found to increase with increase in annealing temperature though not sequentially. For the same energy ranges of the incident photons, the absorption coefficient and refractive index ranged from 0.2 to 1.8 and from 1.4 to 2.3, respectively. The energy band-gap of the films ranged from 1.96 eV to 2.22 eV.

The Structural and Optical Properties of Cobalt dioxide (CoO2 )Thin Films deposited via (SCSP) Technique for photovoltaic applications

“…The FT-IR spectra of the (CoO 2 ) samples, ranging from 4000 to 400 cm -1 , in figure (7) the strong peak was at about 3500 cm -1 which is attributed to the stretching vibration, of the OH group of water molecular[14][15]and hydrogenbound OH groups [16] . The weak band at 1635 cm -1 is due to the bending mode of water molecules.…”

“…Optical conductivity ( ) is expressed in the following relationship [31]: …….. (7) where c: speed of light.…”

“…Five types of cobalt oxide (CoO 2 , Co 2 O 3 , CoO(OH),Co 3 O 4 , and CoO) Cobalt oxide thin films have attracted substantial research effort in recent years because of their potential application in various technological areas. They can be used as high temperature solar selective absorbers [7]. The conductivity of cobalt oxide is usually p-type at low temperature and intrinsic at high temperature [8], measured values of the band gap are around 1.6 eV [9][10].…”

KİMYASAL BANYO DEPOLAMA YÖNTEMİYLE ÜRETİLEN Co3O4 FİLMİNİN OPTİK SABİTLERİ

“…Bununla birlikte, çalışmamızda bulunan n=1,6 kırılma indisi değeri literatürde yapılan çalışmalar ile uyumludur [32][33][34][35]. Kırılma indisi 1,9'un altında olan ince filmler yansıma önleyici (anti-reflecting) malzeme olarak kullanılmaktadır [36]. Dolayısıyla üretilen Co3O4 filminin kırılma indisi 1,9'dan küçük olduğundan bu amaca yönelik kullanılabilir.…”

Optical Properties of Natural Dye Leaf Extracts and Nanostructured TiO2 Particles as Photosensitizers for Dye-Sensitized Solar Cells

“…) above as utilized byDaniele et al, (2010) The energy dispersive X-ray (EDX) characterization was carried out with Phenom Pro X Model, Eindhoven de Netherlands machine. The band gap Eg was determined by using the Tauc relation between the absorption (α) and the incident photon energy (hν), given by the equation 3 as described by(Ekwealor et al, 2015) Αhν = A (hν − Eg) n…”