THE SURFACE AND INTERFACE BEHAVIOR OF EMITTER REGION OF SOLAR CELLS IN PRODUCT LINE

Based on the Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), the specific surface and interface characteristics of emitter region of commercial mono-crystal Si solar cells were examined. Four chemical compositions C, O, Si, and P were detected, and the atomic concentrations (%) of C and O at the surface were much higher than their solid solubility in mono-crystal Si. The high concentration of C and O at the surface was attributed to adhered remains. The single element Si, stable oxide SiO2, as well as intermediate oxidation states such as Si1+ and Si3+ corresponding to Si2O and Si2O3, respectively, have been analyzed. The atomic concentrations (%) of these compositions and their respective chemical states at the surface and interface are likely correlative to the various defects such as electronic-like ramification of hanging bonds, vacancy cluster, or dislocations. Furthermore, the normalized quantum efficiency (QE) of the solar cells made from the wafers was measured to be lower than 74% at short wavelength (< 400 nm), and the influence of surface and interface states on the performance of solar cells was discussed.