Effect of substrate temperature on the microstructure and transport properties of highly (1 0 0)-oriented LaNiO3−δ films by pure argon sputtering

Conductive LaNiO3 films were deposited on (1 0 0) Si substrates by radio frequency (RF) sputtering with pure argon as sputtering gas. Effect of substrate temperature on the microstructure of orientation, crystallinity, surface conditions and electric properties for LaNiO3 films were studied. X-ray diffraction analysis shows that the LaNiO3 films begin to crystallize at 500 °C and exhibit strong (1 0 0)-preferred orientation. Surface morphology observations reveal that with increasing growth temperature, the grain size of LaNiO3 increases monotonously, while the root mean square (RMS) roughness value first gradually decreases and then increases quickly when temperature exceeds 600 °C. A similar tendency is also discovered for the substrate temperature-dependent LaNiO3 resistivity, with lowest resistivity obtained at 600 °C. X-ray photoelectron spectroscopy measurements indicate the loss of oxygen and presence of Ni2+ in LaNiO3−δ films, which coincides with the presence of semi-conductive transport properties based on the temperature-dependent resistivity measurements.