Nitrogenio como um dopante em filmes de a-Ge: H

Antonio Ricardo Zanatta

This work presents experimental data referring to the electrical and optical properties of nitrogen-doped hydrogenated and un-hydrogenated amorphous germanium (a-Ge) films of improved quality. It is shown that the inclusion of minute amounts of nitrogen atoms in the a-Ge network produces important changes in the opto-electronic properties in the material. They can produce large changes in the conductivity of samples having a low density of electronic states in the pseudo-gap. The samples were deposited by RF sputtering a Ge target in an argon plus nitrogen (and hydrogen in the hydrogenated samples) atmosphere. Optical transmission and dark conductivity vs temperature measurements are presented and discussed. The donor level introduced by fourfold coordinated nitrogen is found to be around 60 meV below the conduction band edge. In the a-Ge:N series. absorption bands due to Ge-N vibrations are measured in the IR region of the spectrum. and used to determine the N content. An increase in the density of detects can be observed and associated to nitrogen incorporation. The overall picture is consistent with the doping process of Group V elements in tetrahedrally coordinated amorphous semiconductors. In principle any of the Group V elements (nitrogen. phosphorus. arsenic. antimony and bismuth) could act as donors in a-Ge. Because of the toxicity of such compounds as arsine (AsH3) and phosphate (PH3) which are commonly used for doping. nitrogen appears attractive as a donor material

Nitrogenio como um dopante em filmes de a-Ge: H

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