Properties Of Te Thin Films Research Articles

Optical Properties of Te Thin Films Prepared by Thermal Evaporation Technique

This work describes, Tellurium (Te) films were deposited on glass substrates at room temperature by the method of vacuum evaporation with thickness (0.4µm), with rate of deposition equal to (5.5A/sec), the samples are annealed in a vacuum for one hour at (373 and 433) K. The optical properties such as absorption coefficient () was determined using the absorbance and transmittance measurement from FTIR Shimadzu spectrophotometer, with range of wave length (2800-3900) nm. And also calculated optical constants (refractive index (n), extinction coefficient (k)) for Tellurium films. The tests have been shown that the optical energy gap increases with increasing of annealing temperature for the samples.

Deposition temperature and UV irradiation effects on the H2S sensing properties of Te thin films

In this work, effect of deposition temperature on the microstructure and gas sensitivity of tellurium thin films was studied. Tellurium thin films with different deposition temperatures were deposited on Al2O3 substrate by thermal evaporation. X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) were used for characterizing the prepared samples. XRD patterns indicated that as deposition temperature increased, the crystallinity of the films, also, increased. SEM micrographs showed that the grain size increased and the grain edges became clearer with deposition temperature increase. Studying the effect of depositing temperature on H2S gas sensing properties of Te thin films showed that deposition temperature resulted in an increase in the sensitivity and a decrease in response and recovery times. The results of H2S measurement indicated that the response and recovery times can significantly decrease by application of a UV radiation source before sensing.

Thickness and UV irradiation effects on the gas sensing properties of Te thin films

In this research, tellurium thin films were investigated for use as hydrogen sulfide gas sensors. To this end, a tellurium thin film has been deposited on Al2O3 substrates by thermal evaporation, and the influence of thickness on the sensitivity of the tellurium thin film for measuring H2S gas is studied. XRD patterns indicate that as the thickness increases, the crystallization improves. Observing the images obtained by SEM, it is seen that the grain size increases as the thickness increases. Studying the effect of thickness on H2S gas measurement, it became obvious that as the thickness increases, the sensitivity decreases and the response and recovery times increase. To improve the response and recovery times of the tellurium thin film for measuring H2S gas, the influence of UV radiation while measuring H2S gas was also investigated. The results indicate that the response and recovery times strongly decrease using UV radiation.

Optical Properties of Te Thin Films Prepared by Thermal Evaporation Technique

This work describes, Tellurium (Te) films were deposited on glass substrates at room temperature by the method of vacuum evaporation with thickness (0.4μm), with rate of deposition equal to (5.5Å/sec), the samples are annealed in a vacuum for one hour at (373 and 433) K. The optical properties such as absorption coefficient (k) was determined using the absorbance and transmittance measurement from FTIR Shimadzu spectrophotometer, with range of wave length (2800-3900) nm. And also calculated optical constants (refractive index (n), extinction coefficient (k)) for Tellurium films. The tests have been shown that the optical energy gap increases with increasing of annealing temperature for the samples.

On thickness dependence of electrical and optical properties of Te thin films

The thickness dependences of electrical conductivity, hole mobility, and optical reflectivity are investigated for Te thin films deposited onto glass substrates by thermal evaporation under vacuum. It is found that with an increasing films thickness, the values of these parameters decrease. This behaviour is interpreted, taking into account the specific polycrystalline structure of studied films. By X-ray diffraction studies it was established that in these films the orientation of crystallites changes with an increase in the film thickness. Consequently, we propose a structural model in which the Te thin films are considered as being formed from two superposed layers: the first layer having a preferred orientation of crystallites with their c-axis parallel to the substrate and the second layer with crystallites obliquely oriented to the substrate. The thickness of these sublayers depends on deposition conditions. This structural model is used to explain the thickness dependences.