Determination of piezoelectric and spontaneous polarization fields in CdxZn1-xO/ZnO quantum wells grown along the polar ⟨0001⟩ direction

By iteratively solving the Schrodinger and Poisson equations, we determine theoretical values of built-in electric field induced by spontaneous and piezoelectric polarizations in wurtzite CdxZn1-xO/ZnO (x <= 0.2) quantum wells (QWs) grown along < 0001 > polar direction. By adjusting recent photoluminescence data, we find that this internal field increases with x with a linear slope A = 17.83 MV/cm. Spontaneous and piezoelectric polarization variations are also determined together with the sheet charge densities at CdxZn1-xO/ZnO heterointerface. Our results indicate similar, but much stronger polarization effects than previously reported for MgxZn1-xO/ZnO QWs. They constitute record polarization effects ever reported for wide bandgap heterostructures, including group III-nitrides. (C) 2010 Elsevier Ltd. All rights reserved.