Title :
Electrical Characterization of Cu Composition Effects in CdS/CdTe Thin-Film Solar Cells With a ZnTe:Cu Back Contact
Author :
Li, Jian V. ; Duenow, Joel N. ; Kuciauskas, Darius ; Kanevce, Ana ; Dhere, R.G. ; Young, Matthew R. ; Levi, Dean H.
Author_Institution :
Nat. Renewable Energy Lab., Golden, CO, USA
Abstract :
We study the effects of Cu composition on the CdTe/ZnTe:Cu back contact and the bulk CdTe. For the back contact, its potential barrier decreases with Cu concentration, while its saturation current density increases. For the bulk CdTe, the hole density increases with Cu concentration. We identify a Cu-related deep level at ~0.55 eV whose concentration is significant when the Cu concentration is high. The device performance, which initially improves with Cu concentration then decreases, reflects the interplay between the positive influences (reducing the back-contact potential barrier while increasing the saturation current density of the back contact and hole density in CdTe bulk) and negative influences (increasing deep levels in CdTe) of Cu.
Keywords :
II-VI semiconductors; cadmium compounds; copper; current density; deep levels; doping profiles; electrical conductivity; electrical contacts; hole density; semiconductor doping; semiconductor thin films; solar cells; wide band gap semiconductors; zinc compounds; CdS-CdTe-ZnTe:Cu; back-contact potential barrier; copper concentration; deep level; electrical property; hole density; saturation current density; thin-film solar cells; Admittance measurement; CdTe; capacitance–voltage (CV) characteristics; charge carrier density; contacts; defect;
Journal_Title :
Photovoltaics, IEEE Journal of
DOI :
10.1109/JPHOTOV.2013.2257919
