Physical properties of RF magnetron sputtered GaN/n-Si thin film: impacts of RF power

Abstract

GaN thin film was successfully produced on $$n{\text{-}}Si\left({100} \right)$$ substrate by RF magnetron sputter under different RF power. Experimental measurement techniques such as UV/Vis spectroscopy, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and Micro-Raman Spectroscopy were used to research effects of Radio Frequency power on physical properties of produced thin film. It has been found that produced thin film was polycrystalline structure with (100) and (110) planes of hexagonal $$GaN$$ from X-ray diffraction measurement result. It also proved that increasing RF power gives rise to deterioration in crystal quality of $$GaN$$ thin film. Reason of this deterioration was discussed. It has been achieved that increasing RF power has resulted in decreasing optical band gap energy of $$GaN$$ thin film. Reasons for these changes in optical band gap energy were explained. It was seen that some thin films were grown as layer-plus-island mode (Stranski–Krastanov growth mode) and others were grown as layer-by-layer growth mode (Frank van der Merwe mode) from AFM analysis. It has been found that increasing RF power has resulted in improvement of surface morphology of thin film from field emission scanning electron microscopy analysis. However, reaching RF power to 125 W leads to start to deteriorate of surface of $$GaN$$ thin film. The reasons for this have been discussed. $$E_{1} \left( {TO} \right)$$ transverse optical phonon mode of hexagonal $$GaN$$ with different intensity was detected from Micro-Raman Spectroscopy measurement. The reasons for this difference have been discussed. It was concluded that RF power has played a significant role in growing high quality $$GaN$$ thin film. Morphological, structural, and optical properties of $$GaN$$ thin film were enhanced by controlling RF power, making them a potential candidate for LED, solar cell, diode application.