The unusual nonlinear behaviors of the band gaps in SnxGe1−x alloys are investigated using first-principles calculations. We show that the large bowing of the direct band gap is induced by the disordering effect. Moreover, we calculated individual contribution of the band-edge states and found that the bowing of the conduction band edge is much larger than the bowing of the valence band edge, a...

We discuss the electronic quasiparticle spectrum of a ferromagnetic semiconductor, within the framework of the s-f model. Some exactly calculable limi ting cases (ferromagnetic saturation, atomic limit, centre of gravity of the conduction band, ....) as well as approximate theories for the general case are reviewed in order to understand the influence of temperature and finite band filling on t...

Transparent conductors are neither 100% optically transparent nor metallically conductive. From the band structure point of view, the combination of the two properties in the same material is contradictory: a transparent material is an insulator which possesses completely filled valence and empty conduction bands; whereas metallic conductivity appears when the Fermi level lies within a band wit...

We study the resonance profiles of L 0 phonon and hole intersubband Raman signals from p-type modulation doped AlAs GaAs AlGaAs quantum wells. The resonance profiles show very pronounced sharp peaks at electronic resonance energies. We show that the energies at wh.ich the Raman resonances occur are directly related to the electron subband energies in the conduction band well. We study quantum w...

Electrical conduction in semiconductor heterojunctions containing defect states in the interface region is studied. As the classical drift-diffusion mechanism cannot in any case explain electrical conduction in semiconductor heterojunctions, tunnelling involving interface states is often considered as a possible conduction path. A theoretical treatment is made where defect states in the interfa...

The band structure of strained Si ~4–10 ML! on ~001! GaAs, band lineups of the strained Si/~001!GaAs heterojunction, and confined energy levels of the Si3N4 /Si/GaAs quantum well have been calculated via a pseudopotential method. It has been found that in this technically important Si3N4 /Si/~001!GaAs structure, strained Si has a very narrow band gap ~0.34 eV! at the D' point in the Brillouin z...

A non-optimized interface band alignment in a heterojunction-based solar cell can have negative effects on the current and voltage characteristics of the resulting device. To evaluate the use of Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS) as a means to measure the conduction band position, Cu(In,Ga)S2 chalcopyrite thin film surfaces were investigated as these form the absorb...

The valence band offset (VBO) of wurtzite indium nitride/strontium titanate (InN/SrTiO3) heterojunction has been directly measured by x-ray photoelectron spectroscopy. The VBO is determined to be 1.26 ± 0.23 eV and the conduction band offset is deduced to be 1.30 ± 0.23 eV, indicating the heterojunction has a type-I band alignment. The accurate determination of the valence and conduction band o...

Ballistic-electron-emission microscopy (BEEM) is used to probe local conduction-band structure in strained Sil .xGq layers of pseudomorphic Sil-xGe#Si heterostmctires. The strain variation produced by a roughened Si l.xGex surface is seen as a variation of splitting between thresholds in BEEM spectroscopy. This splitting is directly related to the strain-induced conduction-band splitting in the...