Metallic behaviour at YBaCuO7/Zas interfaces (G=Ga, Al)

Abstract

We present the electronic band structure of the interfaces YBa$_2$Cu$_3$O$_7$/GaAs (direct gap) and YBa$_2$Cu$_3$O$_7$/AlAs (indirect gap) in different configurations calculated using the Density Functional Theory as in the Wien2k code within the local density approximation. We have projected the density of states at the atomic layers forming the interface. We concentrated on the semiconductor side. The four first atomic layers in the semiconductor side of the interface present a clear metallic behaviour. We found for both semiconductors considered that it converges towards the bulk atomic-layer projected density of states a few atomic layers from the interface. We considered an ideal non-reconstructed interface in the (001) direction first and let it relax using the corresponding option in the Wien2k code. The behaviour does not change in an important way and we found but small deviations from the ideal case in the Density of States of the relaxed interface. It is important to relax the interface since the metallic behaviour of the semiconductor side of the could have been suppressed which is the most interesting result of this work. The behaviour at the interface is interesting and could be used in several technological applications and it opens, for example, the possibility to induce superconductivity on the semiconductor side of the metal/semiconductor interface.