INVESTIGATION OF INDIUM-BASED CHALCOGENIDE BUFFER LAYERS PREPARED BY CHEMICAL BATH DEPOSITION PROCESS FOR CIGS PHOTOVOLTAIC DEVICES

摘要

The buffer layers of indium-based chalcogenide compound semiconductor were deposited on the sodalimeglass substrates by the chemical bath deposition (CBD) process. The effects of pH values, acetic acidconcentrations, and thioacetamide concenrations on the surface morphologies and film compositions of In(S,O,OH)films were investigated. The as-deposited films containing indium sulfide, indium oxide, and indium hydroxide wereverified by X-ray photoelectron spectroscopy (XPS) analysis of binding energy spectra of indium and oxygen. Theindium-based buffer layers deposited by the CBD process were thus described as In(S,O,OH) films. The surfacemorphologies of In(S,O,OH) films were assessed by field emission scanning electron microscope (FESEM). Thesmooth surface morphologies of In(S,O,OH) films with a conformal coverage on the glass substrates were achievedby optimizing the pH values, acetic acid concentrations, and thioacetamide concentrations in the deposition bath. Thehexagonal and cubic crystal structure coexisted in the CBD In(S,O,OH) films. The bandgap energy of as-depositedIn(S,O,OH) films was determined from the optical absorption data, revealing the optical bandgap energy of around2.57eV.