Properties of R. F. sputtered CdS thin films

CdS thin films have been prepared using r.f. sputtering in Ar atmosphere. X-ray diffraction studies showed that the films have hexagonal structure with crystallites preferentially oriented in the [002] direction. The crystallite size determined from the broadening of the (002) peak was found to increase with film thickness. The results of electrical conductivity measurements on films with different thickness suggest that the crystallites are undepleted above a thickness of about 500 nm and partially depleted below that value. The intergrain barrier height was determined to be in the range 0 to 0.15 eV in the studied samples. The energy band gap was determined from optical absorption data to be 2.46+/-0.01 eV for the studied films. From the temperature dependence of the electrical conductivity, activation energies in the range 0.12-0.21 eV were determined which agree with previously reported values.