Tsutomu Ishikawa, Masataka Masuda and Yasunori Hayashi
Graduate School of Engineering, Kyushu University, Fukuoka 812-8581Recently, compound semiconductor thin films have been studied very actively for applications to electrical and optical devices that could be the base of the information industry. But the study of metal nitride thin films has not proceeded faster than that of metal oxide thin films. And there are some nitrides that have not been studied on their fundamental properties. In this paper, copper nitride (Cu-N) thin films were prepared by reactive RF sputtering and the relation between electrical properties and sputtering conditions were investigated. As a result, it was clear that the properties of Cu-N thin films were connected with sputtering conditions, especially the content of nitrogen gas and deposition rate of Cu-N thin films. Various Cu-N thin films that were prepared under different conditions had a band gap in the range of 0.5-1.5 eV and their resistivity values were widely changed. Lower values of band gap energy and resistivity than reported values indicated that these Cu-N films are non-stoichiometry and they are supposed to have many defects. Hydrogen implantation treatment of the samples was done in order to improve their properies such as band gap energy, resistivity and carrier density. In result, electrical resistivity drastically decreased from 102 to 10−4 Qm with increasing carrier density. And the structural peculiarity was not influenced by hydrogen implantation. This result shows that implanted hydrogen ions could produce electrons correlated to electrical conduction.
copper nitride, reactive radio-frequency sputtering, band gap energy, resistivity, Hall measurement, hydrogen implantation, stoichiometry, non-stoichiometry