Swift Heavy Ion induced interface mixing in a Te/Cd/Te trilayer thin film system

Abstract

In the present study Swift Heavy Ion (SHI) induced mixing has been investigated at Te/Cd/Te interfaces using 100 MeV 58Ni, 107Ag and 197Au ion beams at a fluence of 5 × 1012 ions/cm2. The films were then characterized by using X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) and UV-Vis spectroscopy. X-ray diffraction (XRD) study reveals the formation of CdTe phase in irradiated samples. The observed ion beam mixing is attributed to the inter-diffusion of atomic species across the interface during transient melt phase. The XRD results show that the average grain size is 28 nm, 20nm and 16nm for the films irradiated with 58Ni, 107Ag and 197Au ion beams at a fluence of 3×1012 ions cm−2.The crystallite size decreases with irradiation of heavier ions. Surface roughness as calculated by AFM is found to increase from 6.7 to 6.8 nm with heavier ions. The optical band gap Egis determined from UV-Vis spectroscopy. The band gap increases from 1.58 eV to 1.74 eV. The increase in band gap as a function of Se, is possibly because of the decreased grain-size.