Low-RF-power growth of InN thin films by plasma-assisted reactive evaporation with a localized ion source

InN thin films were prepared on Si(111) substrate by plasma-assisted reactive evaporation method at low RF power of 100 W and the effect of employing hot filament as a localized ion source (LIS) on the structural, morphological and optical properties of the films was investigated. From the XRD and Raman results it was found that the crystallinity of the films improved as the LIS temperature is increased from 1100 to 1400 °C and after that deteriorated at TLIS= 1500 °C. The XPS showed that InN films with higher quality (less oxygen impurity) can be obtained at the optimum LIS temperature of TLIS= 1400 °C. FESEM images revealed that the uniformity and compactness of the InN samples are highly improved as the LIS temperature is increased from 1100 to 1400 °C. The optical results indicated that the band gap energy of the films is 1.21 eV which is larger than 0.7 eV, possibly due to high carrier concentration and polycrystalline nature of the films, but still desirable for the application in full spectra solar cells.