Effect of RF-power on the optical properties of indium nitride thin films deposited RF-sputtering

Indium nitride (InN) is considered as a promising material for opto-electronic devices because of its direct band gap and good electrical and optical properties. However, there is still a controversy regarding the optical band gap of InN which was reported to vary between 0.6 and 1.9 eV. In this work, InN thin films were deposited by reactive RF-sputtering from a pure indium target in an atmosphere of nitrogen. The films were deposited on unheated glass and silicon substrates. The rf-power was varied from 50 W to 150 W while the substrate-target distance was fixed at 6 cm. There optical transmittance of the films was measured in the wavelength range of 200 - 2500 nm. The as-deposited films were amorphous. Their average transmission of the obtained films were in the visible range is 90%. Interference fringes were observed in the spectra which enabled the determination of the optical parameters of the films. These results will be presented and discussed in addition to those obtained from structural and micro-structural studies of these films.