Energy band structure in p-type germanium and silicon

Second-Harmonic Generation Induced by Electric Currents in GaAs

“…[16] To inject such a current, electrons in a 400-nm thick GaAs crystal, grown along [100], are excited from the valence band to the conduction band by one-photon absorption of a 290-fs, 750-nm pulse and two-photon absorption of a 75-fs, 1500-nm pulse. Both pulses are incident normal to the sample and are tightly focused to 2 -3 µm at the sample surface by using a microscope objective lens.…”

Different Approaches for Multiband Transport in Semiconductors

“…The "coefficients" of this expansion are the so-called envelope functions, which represent a smoothed version of the wave function. The Kane model [3] is obtained choosing as a basis the periodic part of the Bloch functions, the so-called Wannier basis, u n,k (x) [4] evaluated at the point k = 0, where it is assumed that the minimum for the conduction band and the maximum for the valence band in the crystal momentum representation occur (n is the band index and in the case here faced we have n = c, v). The Kane model is represented by a system of two Schrödinger-like equations (here we limit ourselves to the one-dimensional formulation):…”

Comment on ‘‘Calculation of resonant absorption and photoresponse measurement in p-type GaAs/AlGaAs quantum wells’’ [Appl. Phys. Lett. 66, 1659 (1995)]

“…4. For an unpolarized normal-incident radiation, anisotropic effects are incorporated into the oscillator strengths by taking a weighted average 4,7,8 over a set of dielectric functions calculated from energy-subband structures along a number of selected crystallographic directions parallel to the heterostructure interfaces. Nevertheless, we found that anisotropy of the energy subbands is not an important factor in determining the normal-incident-absorption spectra of GaAs/ Ga 1Ϫx Al x As p-QWIPs.…”

“…In addition, the Fermi level of a reasonably optimized p-QWIP is always located 9 next to the energy-subband edge of the initial bound state, such that most of the direct transitions ͓about 60% ͑or 90%͒ at Tϭ77 K͔ would occur 1 in the neighborhood of the two-dimensional Brillouin-zone center, where the magnitudes of the in-plane electron wave vectors are small ͓less than 0.025ϫ2 /a 0 ͑or 0.04ϫ2 /a 0 ͔͒ and the energy contours are nearly circular ͓less than a Ϯ2 meV ͑or Ϯ5 meV͒ variation͔. Besides, anisotropy of the energy subbands is averaged 4,7,8 in the calculation of direct transitions photoexcited from an unpolarized normal-incident radiation. The effects owing to anisotropy of the energy subbands in the normal-incident-absorption spectrum ͑for a GaAs/Ga 1Ϫx Al x As p-QWIP operating at Ϸ9 m and Tϭ77 K͒ are, therefore, insignificant under the combination of the quasi-isotropic momentum-matrix elements, the concentration of direct transitions near the two-dimensional Brillouinzone center, and the averaging of energy-subband anisotropy for an unpolarized normal-incident radiation.…”

“…We would like to point out that the numerical value of the valence-band offset in our previous calculations 1 for GaAs/Ga 0. 7 ready included in the measurements. We have assumed that the influence of the quantum-well width to the exchange energy is negligible.…”