The Proporties of In doped CdZnS films produced by the spray pyrolysis method

ABSTRACT Ph.D. Thesis THE PROPERTIES OF In DOPED CdZnS FILMS PRODUCED BY THE SPRAY-PYROLYSIS METHOD SALİHA DLICAN Anadolu University Graduate School of Natural and Applied Sciences Physics Program Supervisor: Prof. Dr. Muhsin ZOR 2001 In doped CdZnS films have been produced by the spray-pyrolysis method at 250, 275, and 300°C substrate temperatures, and their electrical and optical properties have been investigated. X-ray diffraction spectra of the films showed that they are hexagonal and formed as Cdo.22Zno.78S. The reflection peaks in the spectra shifted towards the smaller angles with the increase of the In concentration. The absorption spectra of the films showed that this compound is a direct band gap material whose band gap values varied between 2.72-3.04eV. All the films showed n-type conductivities. The I-V measurements at room temperature indicate that the conduction mechanism carried out by the space- charge-limited characteristics with two different properties. These are that the ohmic region is either followed by the V2 region or by the trap-filled-limited (TFL) region. The former indicates the presence of the shallow traps, whereas the other indicates the presence of the deep traps which is attributed to the rather high In contents in the materials. The conductivity values (a) varied between 3x1 0"9- 7xl0"7(ohmcm)"1 with the free carrier densities (no) between 2.5xl09- 4.4x10 ^m"3. The activation energies from the Arrhenius plots have been calculated to have values 0.017-0.059eV, 0.237-0.296eV, and 0.558-0.591eV in the temperature regions of 181-247K, 247-300K, and 300-320K, respectively. Key Words: Compound Semiconductors, Spray-Pyrolysis, Space-Charge- Limited Conduction, Shallow and Deep Traps, Activation Energy