Electrical resistance variation in Se(10) Sb(10) Te(80) ternary semiconductor thin films

Thin films of different thicknesses of the ternary semiconductor Se(10)Sb(10)Te(80) have been vacuum deposited at a very fast rate onto cleaned glass substrates at room temperature in a vacuum of 5 × 10-5 torr. I - V characteristics of the thin films have been determined at room temperature and at a higher temperature. Also, the resistance of the different thickness films has been measured as a function of temperature both during heating and cooling. X-ray diffractograms of the films have been taken both before heating the films and after the heating (during the process of measurement). It is found that the I - V characteristics of the films are near-linear both at room temperature and at the higher temperature, indicating that these films cannot be used for making switching devices. The resistance of thin films decreases with the increase in temperature, indicating that the films are semiconducting. The resistances of the films during heating and cooling at a given temperature are slightly different showing that some rearrangement of the microstructure of the films has taken place due to the heating. The thickness dependence of the resistance of the films (at a given temperature) does not apparantly follow the dependence as expected from the size effect theories eventhough there is an increase of resistance for smaller thickness films. The x-ray diffractograms of the films before and after heating also show that eventhough there is no major rearrangement in the films, there is a change in the number of microcrystallites prefering a particular orientation.