Study of Structural Properties of Annealed Cdo and Zno Thin Films

The CdO and ZnO are ntype semiconductors are transparent conducting in nature, inexpensive, mechanically stable and highly resistance to oxidation. In the present work these films have been obtained from thermal annealing of chemically deposited CdS and ZnS thin films. The structural properties of chemically deposited CdS and ZnS thin films and thermally annealed CdO and ZnO thin films have been studied. From x-ray diffraction data it is observed that annealing of the thin films at a particular temperature enhance the structural properties. Article history Received: 02 September 2017 Accepted: 02 October 2017


introduction
CdO and ZnO is an n-type semiconductor belonging to II-VI group of periodic table.These materials possess wide band gap of approximately 2.4eV and 3.3eV at room temperature.These films are semitransparent in nature have been widely used in a flat panel displays, solar cells and gas sensing applications.These films are transparent conducting in nature, inexpensive, mechanically stable and highly resistance to oxidation [1][2][3][4][5] .The CdS and ZnS thin films prepared by chemical bath deposition technique have been extensively studied by many researchers.In the present work we have attempted to annealed CdS and ZnS films prepared by chemical bath deposition to form CdO and ZnO thin films.
The CdO and ZnO films obtained by annealing were characterized for investigation of structural properties.It is observed that annealing effect improve structure of thin films 6 -7 .experimental For the preparation of CdS and ZnS thin films chemical bath deposition technique were utilized.In this apparatus there is a facility for rotating the substrate, stirring the solution using the magnetic stirrer, change the temperature of the entire assembly and stabilized it at a particular value etc.In order to get uniform film thickness the film substrate is continuously rotated and the solution is continuously stirred using magnetic stirrer.The temperature of assembly is maintained by heating arrangement and temperature controller.The thickness of the films governed by controlling the deposition time and the concentration of the solution 8-9-10 .
The prepared samples of CdS and ZnS by chemical bath deposition were taken for annealing and kept into muffle furnaces Biotech of India of 2500 watts at 15 amperes which can withstand maximum temperature of 1000 0 c.The temperature of the furnaces was maintained at 600 0 c for more than 8 hours.After annealing sulfide ions converted into oxide ions by converting CdS into CdO and ZnS into ZnO [11][12] .
The prepared films of CdO and ZnO with annealing effect were taken for characterization to determine structural properties.

result and discussion
Figure 1 show the X-Ray diffraction pattern of CdS thin film obtained using X-Ray generated at 40kv energy and 15mA current without filter.SC 70 detector with the continuous scan mode was used.Qualitative Analysis Result shows that the Phase Name of the film is Greenokite with the formula CdS having DB Card number 1011054.The peak list of the CdS sample is shown in table 1 13,14 .
The thermally oxidized CdO thin film were obtained by annealing the CdS as-depodited at 600 0 C for more than 8hours.The X-Ray diffraction data obtained for CdO thin film given in the table 2 and X-ray reflection peaks shown in figure 2 It is seen from the table2   that the annealing temperature changes the grain size.The prominent reflection peaks are observed at the annealing temperatur6000C as seen in figure 2. The 2theta values corresponds to the particular reflection planes indicating the formation of CdO nanoparticle having pure hexagonal structure which matches with the standared JCPDF data 15,16 .
The XRD pattern of the ZnS thin film was investigated by the Regaku Mimflex 600 Model X-ray diffractometer using PDXL software.This pattern explains the structural properties of ZnS film.The XRD pattern of ZnS sample as shown in figure 3 give three prominent peak at 2θ values 32.620, 35.2950, and 37.0770.The d value1.429A0,1.333A0 and 1.277A0 respectively.These peaks are showing reflection from (100), ( 002) and ( 101) planes, indicating the formation ofZnS nano-particles having cubic zinc blend structure.The enhance intensity for the peak corresponding to (002) plane indicating preference orientation along c-axis.The peak list of ZnS sample is shown in Table 3. 17

Conclusion
The thin film of CdO and ZnO successfully obtained by thermal annealing of CdS and ZnS at 600 0 C. X-ray diffraction analysis of the thermally annealed films CdO film shows that films are polycrystalline in nature.The prominent reflection peaks are observed at the annealing temperatur 600 0 C. The 2theta values corresponds to the particular reflection planes indicating the formation of CdO nanoparticle having pure hexagonal structure.The prominent reflection peaks are observed with the reflection from (100) (002) (101) (102) (110) (103) for ZnO thin film.This data indicate that annealed ZnO thin film is polycrystalline in nature having pure hexagonal structure.It is found that average grain size is obtained which changes due to the change in annealing temperature.