Image Formation in Optical Coherence Tomography and Microscopy

Abstract

This study focused on understanding the mechanisms of the photovoltaic property changes in Zn(S,O,OH)/Cu(In,Ga)Se2 solar cells, which were fabricated via annealing, using reflection electron energy loss spectroscopy (REELS), ultraviolet photoelectron spectroscopy (UPS), low temperature photoluminescence (LTPL), and secondary ion mass spectroscopy (SIMS). A pinhole-free Zn(S,O,OH) buffer layer was grown on a CIGS absorber layer using the chemical bath deposition (CBD). When the Zn(S,O,OH) film was annealed until 200 °C, the Zn–OH bonds in the film decreased. The band gap value of the annealed film decreased and the valence band offset (VBO) value at the Zn(S,O,OH)/CIGS interface with the annealed film increased. Both results contribute to the conduction band offset (CBO) value at the Zn(S,O,OH)/CIGS interface and, in turn, yield a reduction in the energy barrier at the interface. As a result of the annealing, the short circuit current (JSC) and quantum efficiency (QE) values (400–600 nm) of the cell increa...