First demonstration of rectifying property of p-i-n heterojunctions fabricated by tri-layered semiconducting oxides

We have fabricated semiconducting oxide p-i-n diodes in order to explore minority carrier injection effects in oxide materials. The diodes comprised p-La0.85Sr0.15MnO3/i-SrTiO3/n-La0.05Sr0.95TiO3. All oxide layers were grown epitaxially by the eclipse pulsed laser deposition method on (100) SrTiO3 substrates. The diodes showed good rectifying properties, and from the flat-band capacitance measurement, we obtained a diffusion potential of about 0.2,V for these diodes in agreement with the calculated results. In the lower temperature regime, the space-charge-limited-current property was pronounced, arising from residual traps inside the i-SrTiO3 layer. The backward current was mostly due to tunneling through the i-SrTiO3 layer, showing no meaningful expansion of depletion regions in both p- and n-oxide layers.