CORRELATIONS BETWEEN CDTE CDS/SNO2/GLASS SOLAR-CELL PERFORMANCE AND THE INTERFACE SURFACE-PROPERTIES/

Surface and interface properties of CdTe/CdS/SnO2/glass heterojunction solar cells are studied by means of x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and optical reflectance (OR) techniques. First, n-type CdS layer was grown by solution growth technique on the SnO2 coated glass substrate and then the p-type CdTe was deposited on CdS by metal-organic chemical-vapor deposition. Desp ite many other efficiency limiting mechanisms in CdTe solar cells, thi s article shows that surfaces and interfaces play an important role in determining the cell efficiency. In an attempt to correlate the surfa ce and interface properties to the cell performance, a series of CdTe/ CdS solar cells with different conversion efficiencies were fabricated and analyzed. It was found that high efficiency cells possess Te-rich CdTe surface along with smooth interfaces, as revealed by XPS, SIMS, and OR measurements, while low efficiency cells display near stoichiom etric or Cd-rich CdTe surface and abrupt interfaces. The impact and ro le of interface/surface properties on CdTe solar cell performance are discussed. (C) 1996 American Institute of Physics.