Structural, optical properties and VCNR mechanisms in vacuum evaporated iodine doped ZnSe thin films

Iodine doped ZnSe thin films were prepared onto uncoated and aluminium (Al) coated glass substrates using vacuum evaporation technique under a vacuum of 3 × 10⁻⁵ Torr. The composition, structural, optical and electrical properties of the deposited films were analyzed using Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD), spectroscopic ellipsometry (SE) and study of I-V characteristics, respectively. In the RBS analysis, the composition of the deposited film is calculated as ZnSeI_0.003. The X-ray diffractograms reveals the cubic structure of the film oriented along (1 1 1) direction. The structural parameters such as crystallite size, strain and dislocation density values are calculated as 32.98 nm, 1.193 × 10⁻³ lin⁻² m⁻⁴ and 9.55 × 10¹⁴ lin/m², respectively. Spectroscopic ellipsometric (SE) measurements were also presented for the prepared iodine doped ZnSe thin films. The optical band gap value of the deposited films was calculated as 2.681 eV by using the optical transmittance measurements and the results are discussed. In the electrical studies, the deposited films exhibit the VCNR conduction mechanism. The iodine doped ZnSe films show the non-linear I-V characteristics and switching phenomena.