Growth of GaN thin films by RF sputter, investigation of structural, morphological and optical properties

In this thesis, GaN thin films on n-Si, p-Si, sapphire, glass, ITO substrates were grown using RF magnetron sputtering method under different RF power, argon gas and nitrogen gas growth conditions. The structural, optical and morphological properties of the obtained GaN thin films were investigated by experimental measurement techniques. From the XRD analysis, GaN thin films have a hexagonal crystal structure and the crystal grain size, orientations and lattice constants of the material were determined. Thanks to evaluation of AFM measurements, thin films of morphological properties and average surface roughness values were obtained. SEM images proved that materials have almost homogeneous and granular, periodic behavior of structure. Optical band gap energy values of thin films, being a very important parameter for optoelectronic devices, were calculated from UV/Vis absorption measurements. The reflectance ratios of the thin films in the ultraviolet and visible regions were compared according to the growth conditions. It has found that the materials have E(2) (high) and E(1)(TO) optical phonon modes by Raman measurements. Residual stress in GaN thin films were calculated by analysis of Raman measurements. Also, reasons of this stress in thin films were explained by helping with literature studies. In summary, the effects of different growth conditions and the use of different substrates on the structural, optical and morphological properties of the material have been evaluated and analyzed.