Rectifying characteristics and transport behavior of the La_(0.9)Hf_(0.1)MnO_3/Nb-doped SrTiO_3 heterojunction

摘要

La_(0.9)Hf_(0.1)MnO_3 (LHMO) films were grown on (001) SrTiO_3 (LHMO/STO) and (001) 0.7 percent Nd-doped STO (LHMO/STON) substrates under the same conditions by using pulsed laser deposition technique. The x-ray diffraction and rocking curve measurements demonstrated high epitaxy and good crystallinity obtained in our films. The curves of resistance versus temperature indicated that the as-grown LHMO film exhibits a paramagnetic-ferromagnetic transition at Curie temperature T_C. The LHMO/STON heterojunctions exhibited asymmetric current-voltage characteristics similar to those of traditional semiconductor junctions and a typical temperature-dependent rectifying property in a wide temperature range from 20 to 300 K. The diffusion voltage (V_d) of the junction decreases almost linearly with the decrease in temperature. At a negative bias voltage, the dependence of the junction resistance (VII) on temperature showed an insulator-metal transition in the vicinity of T_C, as the voltage decreased from -2 to -7 V. The results were discussed by considering the band diagram of LHMO/STON junction and the tunneling current through the junction.