Structure transition and photoluminescence of CdS/Si nanoheterostructure array on thermal annealing

Highlights: • CdS/Si nanoheterojunctions have been fabricated by growing nc-CdS on Si-NPA. • The variations of PL on the annealed treatment have been observed due to structure transition. • The defect states have been studied by analyzing PL. -- Abstract: CdS/Si heterojunctions have been prepared through growing CdS nanocrystallites (nc-CdS) on the silicon nanoporous pillar array (Si-NPA) by the chemical bath deposition method. Cadmium nanocrystallites (nc-Cd) have been observed and ascribed to the reducibility of Si-NPA. The reason for the appearance of CdO is indistinct and the related work will be done in the future. The blue, green and red emissions are ascribed to the silicon oxide layer, band gap of nc-CdS and the sulphur vacancies, respectively. Redshift and blueshift with the annealing temperature about green emissions are contributed to quantum size effect and the structure transition from nc-Cd to CdO. It is beneficial for investigating the structures and defects to the application of CdS/Si in the optoelectronic field.