Rectifying characteristics of a Fe:SrTiO3/Nb:SrTiO3 homojunction

• We prepared Fe:SrTiO3/Nb:SrTiO3 epitaxial homojunctions.
• We found peculiar rectifying characteristics in the above junction.
• We explained this by the temperature-dependent epsilon of SrTiO3.

Fe-doped SrTiO3 (Fe:STO) thin films have been deposited epitaxially on Nb-doped SrTiO3 (Nb:STO) substrates to form a homojunction. Rectifying characteristics of the Fe:STO/Nb:STO homojunction are studied as a function of temperature. The current under reverse bias is observed to increase dramatically with decreasing temperature. This increased reverse current is ascribed to direct tunneling from the valence band of Fe:STO into the conduction band of Nb:STO, by taking into account the temperature and bias dependence of the dielectric constant of SrTiO3.