Determination Of Band Offsets Research Articles

Internal photoemission — a suitable method for determining band offsets in semiconductor heterostructures

It is shown that band offsets in semiconductors can be studied by internal photoemission experiments. Onsets in the photocurrent are observed for photon energies exceeding the fundamental energy gaps of GaAs and Al x ga 1 − x As. The sign of the photocurrent can be related to the signs of the internal electric fields. An additional photocurrent observed at energies between the two gap energies is related to excitations from the GaAs valence band to the Al x ga 1 − x As conduction band. Extrapolation of the onset energies to flat-band condition leads to ΔE c ΔE g = 0.8 for x = 0.2.

Strain-dependence of localized states in quantum-well structures

A k⋅p model is developed to describe confined states in strained-layer heterostructures fabricated from III–V compounds and their alloys. Unlike the case of simple one-band models, the presence of intrinsic strain not only shifts the band edges but also modifies the effective masses associated with the individual bands. Results for InGaAs/GaAs and InGaAs/InP are presented. We show that the presence of strain can have significant influence on the electronic properties of these systems such as intersubband transition energies and the band offsets. The importance of strain effects on the determination of band offsets from optical data is discussed.

Summary Abstract: Light scattering determination of band offsets in semiconductor quantum wells

Summary Abstract: Light scattering determination of band offsets in semiconductor quantum wells

The role of nonuniform dielectric permittivity in the determination of heterojunction band offsets by C–V profiling through isotype heterojunctions

Up to now, C–V profiling through isotype heterojunctions has been performed assuming a uniform dielectric permittivity throughout the heterostructure. We extend the interpretation of C–V data to the case of a semiconductor with position-dependent dielectric permittivity, and we show that the variation of the dielectric permittivity across an isotype heterojunction interface has no effect on the determination of the heterojunction band discontinuity and the interface charge density.

Determination of heterojunction band offsets by capacitance-voltage profiling through nonabrupt isotype heterojunctions

It is shown that the capacitance-voltage (C-V) profiling technique to obtain heterojunction (HJ) band offsets is grading independent, that is, the band offset values obtained by it are the values for the limit of zero compositional grading, even in nonabrupt junctions. The result explains the good agreement of old data taken on nonabrupt HJ’s grown by liquid phase epitaxy (LPE) with more recent data on abrupt junctions. It suggests that LPE grown HJ’s may be used more freely than was previously thought to determine those offsets, making C-V profiling the most versatile technique for the determination of HJ band offsets.