Synthesis of band gap engineered Pb_xCd_(1-x)Se thin films: A study on their optical, electrical,structural and localized mechanical properties

摘要

In this work, we report a novel electrochemical technique to prepare band gap engineered Ⅳ-Ⅱ-Ⅵ type ternary solid solution system of Pb_xCd_(1-x)Se. This technologically important material is prepared using this method for the first time. We have used a self sufficient modified electrochemical cell made up of Pb anode and a transparent conducting oxide (TCO) coated glass cathode, containing Pb(CH_3COO)_2, Cd(CH_3COO)_2, H_2SeO_3 and Na_2EDTA solutions with proper concentrations as the working electrolyte. X-ray diffraction (XRD) pattern analysis confirms the formation of highly crystalline Pb_xCd_(1-x)Se, whereas, scanning electron micrograms (SEM) reveals a uniform deposition with compact surface morphology. This ternary system showed band gap energy (E_g) of about 1.4 eV, which is in between CdSe (1.77 eV) and PbSe (0.3 eV) and reasonably good for solar energy absorption. Good rectifying behaviour of the TCO/ Pb_xCd_(1-x)Se hetero-junction was established from the current-voltage measurements, which indicate the p-type conduction nature of the deposited ternary compound. Mechanical properties of such thin films were measured by nano-indentation.