Improvement and mechanisms of carriers transportation from the interfaces incorporated by cadmium nanocrystallites in the CdS/Si nanoheterojunctions

Abstract

The defect states in the interface of nanoheterojunctions can trap the separated carriers and reduce the device performance. The approach through incorporating the metal nanocrystallites into the interface can enhance the local electric field to effectively separate and transport the carriers to the corresponding carrier collecting layers and decrease the recombination probability. In this paper, CdS/Si nanoheterojunctions have been fabricated through growing CdS nanocrystallites (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) by using a chemical bath deposition method. Utilizing the reducibility of Si-NPA, cadmium nanocrystallites (nc-Cd) have been incorporated into the CdS-Si interface. After incorporation of nc-Cd into the interface, the forward-to-reverse current ratios, built-in potentials, short circuit current and energy conversion efficiency have been improved. It is indicated that the incorporation of nc-Cd into the interface can decrease the carrier recombination and improve the device performance. This approach will provide an meaningful idea to benefit the carrier separation and transportation, and reduce the recombination.