Power-dependent physical properties of $$\mathbf{GaN}$$ GaN thin films deposited on sapphire substrates by RF magnetron sputtering

Gallium nitride \((\hbox {GaN})\) thin films were grown on the \(\hbox {Al}_{2} \hbox {O}_{3} \left( {0 0 0 1} \right) \) substrate using radio frequency (RF) magnetron sputtering under various RF powers. Many experimental techniques were used for investigating the effects of RF power on the \(\hbox {GaN}\) thin film growth and its physical properties. The X-ray diffraction results confirmed that the \(\hbox {GaN}\) thin film had a polycrystalline structure with planes of \(\left( {101} \right) \) and \(\left( {202} \right) \). The structural parameters of the thin film changed with RF powers. It was also found that the optical band gap energy of \(\hbox {GaN}\) thin films varied with changing RF power. From the atomic force microscopy images, almost homogeneous, nanostructured and a low-rough surface of the \(\hbox {GaN}\) thin film can be observed. From scanning electron microscopy analysis, dislocations and agglomerations were observed in some regions of the surface of the \(\hbox {GaN}\) thin film. \(E_{2}\,({\hbox {high}} )\) optical phonon mode of \(\hbox {GaN}\) was observed, proving the hexagonal structure of the thin film. The residual stress in the \(\hbox {GaN}\) thin films was calculated from Raman measurements. Furthermore, an agreement between the experimental measurements was also examined. The morphological, structural and optical properties of the \(\hbox {GaN}\) thin film could be improved with altering RF power. These films could be used in devices such as light emitting diodes, solar cells and diode applications.