Temperature dependent spin injection properties of the Ni nanodots embedded metallic TiN matrix and p-Si heterojunction

A detailed experimental investigation on magnetic field dependent electronic transport across epitaxial Ni nanoparticles embedded in metallic epitaxial TiN matrix grown on p-type (001) Si substrate heterojunction employing sequential exposure of pulsed excimer laser is reported here. The non-linear current-voltage characteristics along with good rectifying diode like behavior of the junction have been obtained in the range of 100-300 K. The ideality factor, reverse saturation current, series resistance and turn-on voltages have been estimated for the heterojunction at different operating temperatures. The dominating current transport mechanism is found to be temperature dependent tunneling assisted Frenkel-Poole type emission. A crossover from negative to positive junction magnetoresistance (JMR) has been observed at ~ 190 K (blocking temperature of the Ni nanodots). The JMR attains a peak with high positive JMR value at 250 K, the origin of which has been best explained using standard spin injection theory.