Fine-Structured Red-Band Tail Photoluminescence (PL) Spectra of Nanocrystalline CdS:In Thin Films

Abstract

Cadmium sulfide (CdS) is an important material for the manufacture of solar cells and optoelectronic devices. Investigating the photoluminescence (PL) of this material is important for the development of these industries. Nanocrystalline indium-doped cadmium sulfide thin films (CdS:In) have been prepared using the spray pyrolysis method and characterized by x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), x-ray energy-dispersive spectroscopy (EDS), and photoluminescence (PL) measurements. ImageJ software was used to estimate the average size and size distributions of the nanocrystallites and to obtain profile and surface occupancy plots. The PL spectrum was recorded in the wavelength range from 640 to 1280 nm, which covers the red-band tail and part of the near-infrared region. The PL spectra showed fine structure related to the nanocrystalline nature of the films. A deconvolution peak fit was performed to detect the peaks in the region of interest and determine their parameters. The peaks were found to be collected into bands that include doublets. In-depth discussion is presented to explain the origins of the fine structure, the doublets, and the bands.