BAND DIAGRAM OF THE POLYCRYSTALLINE CDS CU(IN,GA)SE-2 HETEROJUNCTION/

Contact potential difference measurements in the dark and under illumi nation are used to derive the conduction band offset (Delta E(c)) in a solar cell quality junction formed by chemical bath deposition of CdS on a polycrystalline thin film of Cu(In,Ga)Se-2. Our experimental mea surements and the estimates made for dipole contributions show that th e junction is of type II, i.e., without a spike in the conduction band (Delta E(c) = 80 meV +/- 100 meV). This is consistent with the high p erformance of the actual solar cell. However, it differs from most pre vious results on junctions based on single crystals and/or vacuum depo sited CdS, which indicated the existence of a conduction band spike. ( C) 1995 American Institute of Physics.