Shakil Khan

Structural and optical analysis of Cr2N thin films prepared by DC magnetron sputtering

Chromium nitride (Cr2N) thin films were prepared by a DC magnetron sputtering technique. The deposition temperature was raised from 50 to 300°C, and its influence on the film structure and refractive index was investigated. X-ray diffraction analysis shows that the crystalline structure of the films transforms from the (101) to (002) oriented hexagonal Cr2N phase as the increase of substrate temperature above 50°C, and a highly textured film grows at 100°C. An empirical relation between the crystalline orientation and infrared active modes of the films is obtained, i.e., the Fourier transform infrared (FTIR) spectrum of the film prepared at 50°C exhibits only A1 (TO) mode. The prominent peak in the FTIR spectra of the film prepared above 50°C is assigned to the E1 (TO) mode and is correlated with the (002) or c-axis oriented hexagonal wurtzite phase of Cr2N. In the surface analysis of atomic force microscopy, a transformation from the featureless surface to columnar-type morphology is observed with the increase of substrate temperature from 50 to 100°C, exhibiting c-axis oriented crystallite growth. A further increase in substrate temperature to 200°C causes the c-axis crystallites to merge, resulting in the formation of voids. The refractive index (n) of the deposited films is obtained using spectroscopic ellipsometry.

Structural characteristics of Ni+-implanted AlN thin film

Metal organic chemical vapor deposited (MOCVD) thin films of aluminum nitride (AlN) were irradiated with 700 keV Ni ions at fluences of 1 × 1012, 1 × 1013, and 1 × 1014 ions cm−2. The stopping and range of ions in matter (SRIM) analysis was performed to investigate the depth distribution of the Ni ions and vacancy production in AlN film. The x-ray diffraction (XRD) patterns of the implanted samples show a shift of the AlN (0 0 2) orientation peak towards higher angles at 1 × 1012 ions cm−2, exhibiting the incorporation of nickel ions into the AlN phase. The XRD patterns also demonstrated a reduction in shift of the (0 0 2) orientation peak along with the formation of AlNi3 phase with the increase of ion fluence. The AFM surface analysis of the ion-irradiated AlN film exhibits a rise of film surface roughness. After ion irradiation, the samples were annealed at 900 °C in a nitrogen environment. Annealing reduces the surface roughness of not only the implanted samples but also the as-grown samples.