An effective dipole theory for band lineups in semiconductor heterojunctions

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Abstract
An effective dipole theory is presented to estimate the band lineups at the interface of a lattice‐matched or nearly matched semiconductor heterojunction. The theory is based on the formation of an effective dipole at the interface which causes additional shift ΔEv in the difference of the band edges. A set of equations are derived from which δEv can be solved iteratively. The calculation requires the values of the top of the valence band and several bulk band‐structure parameters of the constituent semiconductors as input. The dipole effect is evaluated by considering the charge transfer induced by the penetration of the effective mass electrons representing the bulk band states into the quantum barrier of the neighboring semiconductor. The theory is applied to predict the band offset values of more than 100 heterojunctions involving group IV, III‐V, and II‐VI semiconductors. Of the 30 heterojunctions for which the experimental data have been reported, the predicted values differ from the data by only about 0.1 eV on average. Extension of the present theory to several special interface systems is also discussed.