Determination of Defect Distribution in a Ga-rich ZnO/CdS/Cu(In,Ga)Se_2 Solar Cell by Admittance Spectroscopy

Authors: HABİBE BAYHAN

Abstract: This article presents a study on the energy distribution of defects in efficient thin film ZnO/CdS/Cu(In,Ga)Se_2 heterojunction solar cell by the use of admittance spectroscopy. The capacitance spectra of the device has been analyzed using a model based on the existence of a homogeneous distribution of bulk acceptors in the absorber Cu(In,Ga)Se_2 layer. This model reveals an emission from a distribution of hole traps centered at an activation energy of about 300 meV with a defect density of 1.2 \times 10^{17} eV^{-1} cm^{-3}. The band gap of the absorber layer is estimated to be about 1.46 eV which corresponds to a Ga content of about x \approx 0.7 with x the ratio Ga/(Ga+In).

Keywords: CIGS, solar cell, admittance spectroscopy, defect distribution.

Full Text: PDF