Effect of nitrogen flow rate on structural, morphological and optical properties of In-rich InxAl1−xN thin films grown by plasma-assisted dual source reactive evaporation

Abstract

In-rich InxAl1−xN thin films were deposited on quartz substrate at various nitrogen flow rates by plasma-assisted dual source reactive evaporation technique. The elemental composition, surface morphology, structural and optical properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray diffraction (XRD), UV–vis spectrophotometer and photoluminescence (PL) measurements. XPS results revealed that the indium composition (x) of the InxAl1−xN films increases from 0.90 to 0.97 as the nitrogen flow rate is increased from 40 to 100sccm, respectively. FESEM images of the surface and cross-sectional microstructure of the InxAl1−xN films showed that by increasing the N2 flow rate, the grown particles are highly agglomerated. Raman and XRD results indicated that by increasing nitrogen flow rate the In-rich InxAl1−xN films tend to turn into amorphous state. It was found that band gap energy of the films are in the range of 0.90–1.17eV which is desirable for the application of full spectra solar cells.