Laser synthesis of 2D heterostructures of transitional metal oxides for photo sensors with high sensitivity

Abstract

Photons of a KrF laser (248 nm) were used for the synthesis of Cr3−XO3−Y/Fe2O3−X two dimensional (2D) multilayer heterostructures by reactive pulsed laser deposition. Each nanometric multilayer heterostructure with a definite number of layers of iron and chromium oxides was deposited in 2D form on ⟨100⟩ Si substrate at its temperature 293 or 800 K resulted in changing of 2D multilayer heterostructure thickness in the range of 25–85 nm. X-ray diffractometer analysis confirmed polycrystalline structure of these deposits. Element analysis was carried out by an energy dispersive x-ray spectroscopy. All synthesized 2D multilayer heterostructures demonstrated semiconductor temperature trend with variable equivalent energy band gap (Eg) in the range of 0.36–0.87 eV. The more substrate temperature was the more Eg value, and the more 2D multilayer heterostructure photosensitivity. Optimum experimental parameters were found out to obtain the highest photosensitivity of 2D multilayer heterostructure. Highest obtained photosensitivity was high as 420 VC/W at white light power density ∼6 × 10−3 W/cm2. VC is “chemical” photo electromotive force induced in the deposited 2D multilayer heterostructure while it irradiating with a white light, W is white light power. High photosensitivity nature of the 2D multilayer heterostructure synthesized on a heated substrate was explained. Therefore, such 2D multilayer heterostructures of iron and chromium oxides exhibiting high photosensitivity are exceptionally a strong candidate for effective photo sensors of white light.