Sequential Deposition of NbN/MgO Film on Si(100) Using Pulsed KrF Excimer Laser Deposition Method with Different Ambiences

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Abstract
Sequential formation of NbN/MgO bilayers on Si(100) using pulsed KrF excimer laser deposition with different ambiences of oxygen and nitrogen has been performed. The effects of nitrogen ambience on the NbN formation in this sequential process are examined. The deposited films are characterized by X-ray ( Cu-Kα) diffraction, X-ray photoelectron spectroscopy and measurement of the critical temperature of superconducting transition. The concentration of nitrogen in the NbN film increases with the ambient pressure up to 9×10-2 Torr and superconducting transition is observed at ∼12.7 K. However, the plume distribution became broader with increasing N2 gas pressure and non- negligible oxidation of the NbN films occurred. The reasons for the oxidation problem are related to the enhancement due to the multiple collisions between the ablated particles and oxygen impurity, which is mainly generated by resputtering from the surfaces of both the previously deposited MgO film substrate and its holder.