Determination of piezoelectric and spontaneous polarization fields in CdxZn1−xO/ZnO quantum wells grown along the polar 〈0001〉〈0001〉 direction

By iteratively solving the Schrödinger and Poisson equations, we determine theoretical values of built-in electric field induced by spontaneous and piezoelectric polarizations in würtzite CdxZn1−xO/ZnO (x≤0.2x≤0.2) quantum wells (QWs) grown along 〈0001〉 polar direction. By adjusting recent photoluminescence data, we find that this internal field increases with xx with a linear slope A=17.83MV/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.