The influence of series resistance on the I-V characteristics of CdTe thin films

The influence of series resistance (Rs) on the current (I) – voltage(V) characteristics of evaporated cadmium telluride(CdTe) thin films has been investigated. CdTe films of thickness 1000Å were deposited by thermal evaporation in a vacuum of about 10-5torr. For the I – V measurements, the two point probe configuration was adopted using aluminium electrodes. The experiment was conducted in controlled atmosphere where the temperature was varied from 303 to 333k. The I – V measurements reveal that at applied voltages below 40V, the conduction is ohmic while at voltages above 40V, there is departure from linearity due to series resistance. The evaluated values of series resistance vary from 520 to 1000 K as the temperature varies from 303 to 333K. The surface conductance of CdTe increases with temperature according to the relation, = o exp(-/kT). The activation energy calculated from this empirical relation is 0.7eV. Also, the barrier height of Al- CdTe junction was determined and found to be 0.75eV. (Botswana Journal of Technology: 2002 11(2): 29-33