Influence of bath temperatures on physical and electrical properties of potentiostatically deposited Cu_2O thin films for heterojunction solar cell applications

摘要

In the present work, the influence of bath temperatures on structural, morphological, vibrational, optical, electrical and photo response properties of the electrochemically deposited cuprous oxide (Cu2O) thin films on fluorine doped tin oxide substrate is extensively investigated with the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), Micro Raman spectroscopy, photo luminescence (PL) spectroscopy, UV-visible spectroscopy, LCR measurement, Keithley 4200 semiconductor characterization system respectively. XRD patterns reveal that the deposited Cu2O films have cubic structure grown along the preferential (111) orientation and the film deposited at 40 A degrees C shows better crystalline nature when compared at 55 and 70 A degrees C. The micro structural properties of films such as crystallite size (D), dislocation density (delta), micro strain (epsilon) and stacking fault probability (alpha) were calculated and discussed in detail. SEM displays a well-defined three side pyramid shaped morphology for the film deposited at 40 A degrees C. Micro Raman and PL spectra reveal the film deposited at 40 A degrees C by being better crystalline at a higher acceptor concentration. UV-Visible study shows that the optical energy band gap increases from 2.05 to 2.17 eV with an increase in bath temperature from 40 to 70 A degrees C. The frequency-temperature dependence of impedance analysis shows a higher electrical conductivity for a film deposited at 40 A degrees C compared to other bath temperatures. I-V measurement illustrates a good photoconductivity response for Cu2O thin film deposited at 40 A degrees C compared to films deposited at 55 and 70 A degrees C.