Fabrication Characterization, And Photovoltaic Application Of Semiconducting Fe₂o₃ Thin Films Deposited By Pulsed Laser Deposition

Semiconducting Fe₂O₃ thin film is a multi-purpose metal oxide material, and has a lot of advantages such as non-polluting, resource-rich, stable performance, and so on. Iron oxide has been used in many fields such as catalyst for hydrogen production, battery electrode materials for organic electrolyte solution, gas sensors, and magnetic memory materials. Besides, the band gap of iron oxide thin films is about 2.0eV, which is near to the peak wavelength of solar spectrum, making it possibe for solar cell applications. However, a few data are available in the literature concerning the characterization and application of Fe₂O₃ as solar cell applications. Therefore, the research on optical and electrical properties of iron oxide thin films has a great significance for the exploration of new materials for solar cells.This paper overviews the prospect of solar cells development and requirement of materials for future solar cells, and summarize the advantages and disadvantages of the iron oxide thin film preparation methods. The pulsed laser deposition (PLD) method was at last selected to deposit Fe₂O₃ thin films, and the the chemical composition, crystal structure, optical properties, electrical properties and surface morphology of iron oxide thin film has been studied. Based on the study, an iron oxide-based solar cell structure was fabricated. The result is as follows:The iron oxide thin films have been deposited on glass substrate using pulsed laser deposition (PLD) method, and X-ray diffraction and X-ray photoelectron spectroscopy were employed for the analysis of its chemical composition, and it show that the as-prepared films are Fe₂O₃ thin films.The film crystallization is invetigated as a function of the substrate temperature, oxygen flow rate, deposition time, substrate material properties, and it is found that substrate temperature is the main influent factor for thin film crystalline quality.The optical properties of Fe₂O₃ thin films is studied in the term of substrate temperature, oxygen flow rate, deposition time, substrate material properties, and it is found that the direct band gap of the film is 1.73eV 2.0eV and the indirect band gap is 1.47eV 1.52eV.The electronic properties of Fe₂O₃ thin films is studied as the function of the substrate temperature, oxygen flow rate, deposition time, substrate material properties, and it is found that the minimum conductivity of undoped Fe₂O₃ thin film is about13.28Ωcm. Besides, the cuurent-voltage characterization of Fe₂O₃ thin film has been studied, and it's found that the breakdown voltage of Fe₂O₃ thin film is 6.6V.The surface morphology and structure of Fe₂O₃ thin films is studied in the term of different substrate temperature, oxygen flow rate, deposition time, substrate materials, and it's found that under the low substrate temperature, grain size of thin film is smaller, but the surface is smooth. If the substrate temperature is high, thin film grain size is larger, but the surface is rough. Besieds, the substrate used for the preparation of Fe₂O₃ thin films is related to the surface morphology. The films deposited on silicon substrate has the best surface morphology, followed the quartz substrate and the glass substrate.(6)The p-Si /n- Fe₂O₃ junction solar cells were fabracated, and their photovoltaic performance has been investigated. The result show that the maximum open circuit voltage is 105mV, and the maximum short-circuit current density is 54.5 mA/cm². Compared with silicon solar cells, the result we achieved in this work is not so good, but considering the simple equipment and process, the acheived results have proved that Fe₂O₃ is a promising material for solar cell applications.