Spectroscopic investigation of Cu_x Mg_0.2-x Zn_0.8 S (x = 0, 0.05, 0.10, 0.15) thin films for deep and dilute blue LED...

The effect of copper (Cu) doping on the luminescent properties of the spray deposited Mg_0.2 Zn_0.8 S thin films were investigated for the first time. The Mg_0.2 Zn_0.8 S film is an excellent luminescent material with strong blue emissions. In the current investigation, we doped Mg_0.2 Zn_0.8 S with Cu by taking (Cu + Mg) as 20 at% by keeping other element ratios constant. Among the different samples in the series, Cu_0.05 Mg_0.15 Zn_0.8 S has shown promising results with dark blue emission. Also, these films showed good structural formation with lower or no other impurities, which is evident from the X-ray diffraction (XRD). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) confirmed the improved material quality of Cu_0.05 Mg_0.15 Zn_0.8 S as compared to the pristine. Raman and X-ray photoelectron spectroscopy (XPS) studies have been carried out for the samples. Various defects induced in the films were investigated by recording the photoluminescence (PL) spectra and Cu:(Mg_0.2 Zn_0.8 S) films exhibited the capability to produce dilute blue luminescence by absorbing ultraviolet (UV) light. The Cu_0.05 Mg_0.15 Zn_0.8 S film showed promising material property, which is suitable for light-emitting diode (LED) applications.