Study of point defects in ns pulsed-laser annealed CuInSe2 thin films

Abstract

Pulsed-laser annealing (PLA) of Cu(In,Ga)Se2 thin films has been shown to improve their optoelectronic properties. Here we investigate the effects of ns PLA on the identity of traps in CuInSe2 films prepared by electrodeposition followed by furnace annealing with Se. Raman spectroscopy indicates a decrease in width of the A1 phonon peak and relaxation of compressive strain after PLA. Current-voltage measurements indicate improvement in ideality factor of heterojunction diode cells built from laser irradiated films. Defect spectroscopy on Schottky diode and complete solar cell reveal similar defect level for EDA_ref sample present at ≈ 200 meV. However for the sample processed at 30 mJ/cm2 we find a deep trap at ≈ 300 meV in case of Schottky diodes, whereas complete solar cells show a trap at ≈ 60 meV.