Electronic properties of PLD prepared nitrogenated a-SiC thin films

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• 作者：Barreca ; Francesco ; Fazio ; Enza ; Neri ; Fortunato ; Trusso ; Sebastiano
• 关键词：a-SiCN ; Electronic properties ; Laser ablation
• 刊名：Thin Solid Films
• 出版年：2003
• 出版时间：June 2, 2003
• 年：2003
• 卷：433
• 期：1-2
• 页码：34-38
• 全文大小：239 K

文摘

The electrical transport properties of a set of amorphous SiC_xN_y thin films have been investigated in the temperature range from 100 to 530 K. Information about the stoichiometry and the structural properties of the samples have been obtained by means of X-ray photoelectron spectroscopy, while the optical band gap was obtained by means of spectroscopic ellipsometric measurements. A widening of the optical band gap E_g from 1.6 eV up to 2.4 eV was observed as the nitrogen content of the samples increased up to 7.5 % . Two distinct electrical conduction mechanisms were observed at high and low temperature, and attributed to the conduction in band, or band edge, states, and to activate nearest-neighbour hopping, respectively. The activation energy of the high temperature conduction mechanism was found to increase from approximately 0.2 eV up to 0.9 eV, increasing the nitrogen content, while the room temperature dark conductivity decreased from 10⁻⁵ to 10⁻⁹ Ω⁻¹ cm⁻¹. Such findings are compatible with a reduction of band gap states and a simultaneous widening of the gap itself, as a result of nitrogen incorporation, and was related to the increase of the SiN over SiSi bond number ratio as reported by the XPS analysis.