NANOINDENTATION INVESTIGATION OF THE REACTIVE PULSED LASER DEPOSITED SUPERCONDUCTING NIOBIUM NITRIDE THIN FILMS

摘要

Nanomechanical properties were investigated for the reactive pulsed laser deposited(PLD)superconducting NbN_x thin films grown on Si(100)at constant substrate temperature of 800°C using three different background nitrogen gas pressures(200, 400 and 500 mTorr). The Cross-sectional transmission electron microscopy(TEM), X-ray diffraction(XRD), and atomic force microscopy(AFM)were employed to characterize the films' surface structure and morphology. Superconductivity was determined by performing resistance measurements. Nanoindentation technique was used to evaluate the hardness and modulus of the films. The results indicate that the background pressure impacted the crystalline quality, morphology, superconductivity and the hardness of the films. As the background pressure increases to 500 mTorr, improved superconducting properties and higher hardness(17.5±1.5 GPa at 20 nm depth)values were reported as compared to the other two samples.