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

摘要

We studied the effects of adding yttrium (Y) in bulk lanthanum aluminate (LaAlO_3 or LAO) by investigating the quaternary compound oxide, lanthanum yttrium aluminum oxide La_(0.3)Y_(0.7)A1O_3 (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 AI/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.