Title :
New cadmium-free buffer layers as heterojunction partners on Cu(In,Ga)(S,Se)2 thin film solar cells
Author :
Eisele, W. ; Ennaoui, A. ; Schubert-Bischoff, P. ; Giersig, M. ; Pettenkofer, C. ; Krauser, J. ; Lux-Steiner, M. ; Riedle, T. ; Esser, N. ; Zweigart, S. ; Karg, F.
Author_Institution :
Hahn-Meitner-Inst., Berlin, Germany
Abstract :
A Zn(Se,OH) buffer layer deposited by chemical bath process on Cu(In,Ga)(S,Se)2 (CIGSS) absorbers is investigated. Before deposition of the actual ZnSe layer, the absorber is immersed in a Zn-containing solution (Zn treatment). Transmission electron microscopy (TEM) pictures of the buffer layer exhibit two different areas: a dark structured layer containing small crystals of ZnSe and a bright amorphous layer, which is thought to consist of Zn(OH)2 predominantly. We suggest that already during the Zn treatment an amorphous buffer layer is growing. X-ray photoelectron spectroscopy (XPS) measurements of the Cu2p and O1s peak of Zn-treated absorbers show a coverage with an OH component, attributed to Zn(OH)2. Nuclear reaction analysis (NRA) measurements reveal a peak hydrogen concentration of 8×1021 H/cm3 in the buffer layer. Micro-Raman spectra show a shift of the LO branch of ZnSe from 250 cm-1 to 258 cm-1
Keywords :
ESCA; Raman spectra; X-ray photoelectron spectra; amorphous semiconductors; copper compounds; gallium compounds; indium compounds; liquid phase deposited coatings; nuclear chemical analysis; solar cells; ternary semiconductors; transmission electron microscopy; zinc compounds; 250 to 258 cm-1; Cd-free buffer layers; Cu(In,Ga)(S,Se)2 thin film solar cells; Cu(InGa)(SSe)2; LO branch; OH component; TEM; X-ray photoelectron spectroscopy; XPS; Zn treatment; Zn(Se,OH) buffer layer; Zn(SeOH); Zn-containing solution; bright amorphous layer; chemical bath process; dark structured layer; heterojunction partners; micro-Raman spectra; nuclear reaction analysis; peak hydrogen concentration; Amorphous materials; Buffer layers; Chemical processes; Crystals; Heterojunctions; Hydrogen; Nuclear measurements; Spectroscopy; Transmission electron microscopy; Zinc compounds;
Conference_Titel :
Photovoltaic Specialists Conference, 2000. Conference Record of the Twenty-Eighth IEEE
Conference_Location :
Anchorage, AK
Print_ISBN :
0-7803-5772-8
DOI :
10.1109/PVSC.2000.915960
