Defect Characterization of III-V Quantum Structure Solar Cells Using Photo-Induced Current Transient Spectroscopy

Abstract

Radiation degradation characterization method for solar cells embedded with quantum dot (QD) layers using Photo-Induced Current Transient Spectroscopy (PICTS) is proposed in this study. Contrary to Deep Level Transient Spectroscopy (DLTS), PICTS is capable of comparing directly photo-current degradation to radiation induced defects for p-i-n structure solar cells, which is a basic structure of QD solar cells. GaAs p-i-n solar cells with 50 In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> As QD layers are fabricated by Molecular Beam Epitaxy (MBE) and the radiation degradation is investigated by PICTS measurement. The current-voltage characteristics under AM0, 1 sun condition is also investigated and the degradation of solar cell performance is discussed by comparison to defect levels obtained from PICTS spectra. GaAs p-i-n solar cells without QDs are also investigated for comparison.