cbd cds

The role of thermal annealing and of CdCl 2 as a main source of electrically active but vaporizable chlorine doping in chemical bath deposited CdS thin films is studied. The films were deposited on glass substrates from aqueous solution of either CdCl 2 , NH 4 Cl, NH 4 OH, and thiourea, or CdSO 4 , (NH 4 ) 2 SO 4 , NH 4 OH, and thiourea. Films deposited in the presence of CdCl 2 and annealed in H 2 atmosphere at 310 and 420 °C show a resistivity lower than 10 Ω·cm, one order of magnitude less than for identically annealed films deposited in absence of CdCl 2 . Annealing at 420 °C in closed ampoules, where a counter pressure of CdCl 2 builds up, leads to a lower resistivity on the order of 10 −1 Ω·cm, confirming the key role of chlorine on the electronic properties. However, further characterization via photoluminescence raises new questions about chlorine-related defects and their role in the mechanisms that govern film resistivity.

Cadmium sulphide (CdS) thin films have been deposited by chemical bath deposition method (CBD) on CdTe substrates. The temperature of the deposition was varied from 40 oC to 70oC under stirring, pH of complexing agent about 10-11.5 and doping by CdCl2. The morphology was composed of small columnar crystals, characterized by SEM. The crystallographic structure contains a mixture of hexagonal and cubic structures were study by TEM. The energy gap values 2.395 eV were found calculated by reflectance spectra using UV-VIS spectrometer. This study showed the correlation of deposition temperature, grain size, energy gap and observed some properties of CdS nanocrystal in the films.