Minority carrier traps in Cu(In,Ga)(S,Se)2 solar cells

Cu(In,Ga)(S,Se)2 (CIGSSe)/buffer/ZnO:B heterojunction solar cells were fabricated with two different buffers, CdS (Sample A) and Zn(S,O) (Sample B), which were prepared using a chemical bath deposition wet process and an atomic layer deposition dry process, respectively. The diode properties and deep center properties of Samples A and B were examined as current-voltage, capacitance-voltage, and deep-level transient spectroscopy measurements. Two minority N1 (electron) traps were observed in each CIGSSe solar cell, the activation energies of which were 466 meV and 317 meV in Sample A and 329 meV and 247 meV in Sample B, respectively. The activation energy of the N1 level attributed to the InCu-compensating donors, i.e., InCu (+/++) and InCu (0/+) antisite defects, varies with changes in the electric field and potential distribution within the junction.