Photoreflectance (PR) spectroscopy เป็นวิธีการตรวจสอบแถบพลังงานของฟิล์มบางอินเดียมไนไตรที่ปลูกด้วยกรรมวิธี rf magnetron sputtering /The photoreflectance (PR) spectroscopy was used to investigate the band-gap energy (Eg) of indium nitride (InN) thin films grown by rf magnetron sputtering with different ratio frequency (rf) power. The reactive gas-timing technique for sputtering process is successfully to grow InN thin films. The X-ray diffraction (XRD) patterns exhibited strongly peaks in the orientation along (002) and (101) planes corresponding to polycrystalline hexagonal-InN structure. The band-gap transition energy of InN was determined by fitting the PR spectra to a theoretical line-shape expansion. The PR results showed the band-gap energy at 1.18 eV of InN thin films grown by rf power at 100 and 200 Watt. The high excited nitrogen ions obtained from high rf power of sputtering with gas-timing technique can effectively to formation of InN without substrate temperature.