Synthesis of α-In 2 Te 3 thin films from In/Te bilayer by Si ion irradiation

Abstract

In this work, In/Te bilayer thin films were prepared using sequential thermal evaporation method and subsequently irradiated using swift heavy ions (SHIs) of 100 MeV silicon (Si) with different fluences (1×1013 to 5×1013/cm2). The inter-diffusion of In and Te layers was highly controlled by SHI irradiation and the In2Te3 formation capability was compared with that of the conventional annealing method. The structural as well as optical properties of a post-sintered SHI-irradiated In/Te bilayer were investigated using X-ray diffraction (XRD) measurements and UV–visible spectroscopy, respectively. We found that irradiated samples showed single-phase In2Te3 under post-annealed conditions at 150 °C unlike that prepared using the conventional thermal annealing method, which showed mixed phases under similar conditions. This confirms the effective inter-diffusion in bilayer films by SHI irradiation toward the formation of single-phase In2Te3. The estimated optical band gap energy was found to be 1.1±0.5 eV and strongly corroborated the XRD results. In addition, the estimated refractive index (n) value of the SHI-irradiated sample (∼3.3) was higher than that of the sample obtained through the conventional annealing method (∼2.8). This proves that SHI offers a highly compact nature even at low temperatures. This work has a wide scope for achieving single-phase alloyed films through bilayer mixing by SHI irradiation.