Superconductivity and mixed-state characteristic of InN films by metal-organic vapor phase epitaxy

We have performed resistivity, magneto-resistance and Hall resistance measurements on metal-organic vapor phase epitaxy (MOCVD) grown InN films on Si substrate. Superconducting phase transition and anomalous mixed-state behavior were observed in wurtzite-structured InN thin films. The resistance is metallic like over a wide temperature range (4 K ≤ T ≤ 300 K) and R (300 K) / R (4 K) is about 1.1. The carrier concentration and mobility measurements show the InN thin films in this range a degenerate electronics system. However, the resistivity starts to change at 4 K, which makes the slope of the temperature dependence larger at 1.5 K. Then it become less then 10^{- 3} at 0.3 K. The films show positive magnetoresistance (PMR) between 0.3 and 4 K at B_// (B // c-axis of InN) < 0.8 T. The PMR can be understood as superconductor mixed state behavior and origin from the flux dynamics. We measured Hall coefficients of InN thin films in the superconducting mixed states. Anomalous Hall effects were observed at 0.3 K. There is no Shubnikov-de Haas (SdH) oscillations observed until B is 15 T. Details are discussed in the paper.