Energy states in ZnSe-GaAs heterovalent quantum structures

We investigate the energy states in ZnSe-GaAs heterovalent quantum structures. In the ZnSe-GaAs heterovalent heterostructures, the band offsets are controllable, and therefore different offsets can artificially be put at both sides of the GaAs wells through the control of the growth sequence fanning the interfaces, which brings unique characteristics on the heterovalent quantum structures. The characteristic features are examined by the optical-absorption measurement. Dependence of the absorption edge on the offsets and the well width reveals the presence of an electric field; by changing the valence-band offset at one side of the GaAs well from 0.6 to 1.1 eV, while keeping that at the other side constant at 0.6 eV, we observe that the absorption edge energies are shifted toward lower energy and that the degree of the redshift depends on the GaAs well width. These experimental results are well explained by the theoretical calculation of the Poisson and Schrodinger equations. On the other hand, the barrier width dependence exhibits the anomalous behavior that cannot be expressed by the theoretical analyses and is interpreted in terms of the charge transfer within the barrier region. [S0163-1829(99)15047-1].