Layer-by-layer engineering: shifting band alignments

The ability to grow materials layer by layer with atomic precision opens the door to control and engineering of materials properties. During the growth of SrTiO3, we can insert a pair of atomic layers of LaAlO3 as shown at left. Our first principles theory shows that the polar nature of inserted LaO and AlO2 layers causes a shift between electronic band energies of the SrTiO3 on the two sides. Repeated insertions of such layers should allow experimenters to create larger accumulated shifts as well as quantum wells that can trap electrons for further control over their properties

Band energy shift delta V at various levels of theory:

  • Bare LaO /AlO2- charged sheets : 24 eV
  • Electronic screening of SrTiO3 : 4.5 eV
  • Ionic electronic screening : 0.5 eV
SrTiO3-LaAlO3-SrTiO3 layer system 0.5 eV from first principles
Wednesday, December 18, 2013