Effects of the MoN diffusion barrier on the CZTSe growth behavior and solar cell performance

Earth-abundant and low-toxic Cu2ZnSnSe4 (CZTSe) kesterite-compound semiconducting absorbers were deposited on bare Mo(600 nm) and Mo(10 nm)/MoN(50 nm)/Mo(600 nm) substrates using a two-stage selenization process. The effects of the MoN barrier on the properties of the CZTSe films and device performance were investigated. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy showed that the addition of a MoN barrier layer resulted in a decrease in the MoSe2 layer thickness. Raman depth analysis showed that for the bare Mo substrates, the ZnSe phase was distributed from the middle to the surface of the absorber, whereas it was distributed at the bottom for the MoN barrier substrates. MoSe2 formation was suppressed greatly with the MoN barrier layer. On the other hand, the current-voltage curve of the device was distorted significantly by the incorporation of the MoN barrier layer. The electro-optical properties will be discussed in conjunction with the ZnSe distribution in the absorber layers. (C) 2018 Elsevier B.V. All rights reserved.