  Amorphous insulating oxides play a significant role in the contemporary
electronic industry. Understanding the band alignment of heterogeneous
interfaces containing amorphous structures helps to better control the carrier
transport property at the interface. Classical band offset methods developed
previously line-up eigenlevels with respect to an ideal bulk reference or
vacuum level. However, the local disorder of amorphous structures makes the
bulk reference ambiguous. Therefore, classical methods cannot be applied. In
this study, we introduce a new approach based on the Linear Combination of
Atomic Orbital (LCAO) projection of wave-function to line-up bands at
metal/oxide interfaces. The LCAO projection of wave-function accounts for all
metal/oxide interface effects, such as build-in voltage, interface dipole,
virtual oxide thinning, barrier deformation, etc. Therefore, it provides
accurate band alignments. Calculations performed at an Al/amorphous-SiO2
exhibit a good agreement between existing experiments and simulation data. We
Also observed a space charge region at the interface resulting in non-linear
band bending in the oxide, which virtually decreases its thickness, hence
lowering the dielectric strength.

Materials Science