| Description |
Semiconductor devices are essential components in much of modern technology. The first step in producing semiconductor devices lies in understanding the properties of semiconducting materials. This research seeks to aid in the understanding of doping mechanisms in amorphous semiconductors. Specifically, doping in the amorphous chalcogenide material CuAsS was studied. Varying amounts of oxygen or cadmium were incorporated into thin sputtered films of CuAsS in attempt to dope the material. The temperature dependence of the films' conductivity was measured, and the results showed that oxygen dramatically increases conductivity and decreases activation energy. Cadmium was observed to have the opposite effect of decreasing conductivity and increasing activation energy. All samples were determined to be ptype, although the cadmium samples have a Fermi level above that of the nominally undoped samples (which are inherently p- type) . Optical absorption was measured for each sample and was used to confirm that the band gap energy was not changed significantly with the addition of these impurities. This result combined with the changing activation energy is used to show that the impurities serve to move the Fermi level of the material within a fixed band gap. This indicates that doping has been achieved in this amorphous chalcogenide material, and the results are consistent with a previous study of the related system CuAsSe. Understanding the doping mechanisms in these materials will help to develop an understanding of doping in amorphous semiconductors in general. |
