Band gap, band offsets and dielectric constant improvement by addition of yttrium into lanthanum aluminate

Abstract

We studied the effects of adding yttrium (Y) in bulk lanthanum aluminate (LaAlO3 or LAO) by investigating the quaternary compound oxide, lanthanum yttrium aluminum oxide La0.3Y0.7AlO3 (LYAO), on silicon (Si). It is found that the inclusion of Y to LAO increases the band gap by ∼0.9 eV without compromising the dielectric constant. The enhancement in the band gap results in larger band offsets in LYAO and we also observe a decrease in leakage current at low voltage accumulation bias for Al/LYAO/Si as compared to Al/LAO/Si. In addition, the interface trap density of the Al/LYAO/Si structure remains comparable to that of Al/LAO/Si. Our findings show that LYAO is an attractive high dielectric constant material for use in next-generation low standby power devices. © 2013 Elsevier B.V.