TEM studies of pulse electrodeposited Cu-Se and CuInSe₂ films

Abstract

Photovoltaic technology is considered as one of the major options for large-scale energy production without pollution. Thin-film technologies are seen as a potential approach to produce cost-effective electricity by photovoltaic. Among the different thin-film deposition techniques (CVD, vacuum evaporation, sputtering, etc.), electrodeposition has emerged as a low-cost method. Using a pulsed electrodeposition technique semiconductor thin films of Cu-Se and CuInSe 2 with improved uniformity and lower impurity have been prepared. Varying the electrodeposition solution pH, stoichiometric CuSe, Cu 3 Se 2 , Cu 2 Se and Cu 2 Se films on Indium Tin Oxide (ITO) coated glass or Ni electrodes were obtained. Their composition and properties varied with heat treatment (3). This paper reports the detailed study by Energy-Dispersive Spectrometry (EDS) and Transmission Electron Microscopy (TEM) of heat treatment effects on the composition and phase changes. EDS analyses were done on films deposited onto ITO glass using an Hitachi S-530 Scanning Electron Microscope (SEM). Cerac 99.99% pure powders were used to establish EDS calibration spectra. TEM studies were done on films directly deposited onto Ni grids. Selected area diffraction pattern (SADP) analyses were used to identify the structures. Samples were examined in a Philips EM-300 TEM operated at 100 kV.