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تسجيل مستخدم جديدInfluence of the magnetopolaron effect on light reflection and absorption by a wide semiconductor quantum well
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Light reflection and absorption spectra by a semiconductor quantum well (QW) , which width is comparable to a light wave length of stimulating radiation, are calculated. A resonance with two close located exited levels is considered. These levels can arise due to splitting of an energy level of an electron-hole pair (EHP) due to magnetopolaron effect, if the QW is in a quantizing magnetic field directed perpendicularly to the QW plane. It is shown that unlike a case of narrow QWs light reflection and absorption depend on a QW width $d$. The theory is applicable at any ratio of radiative and non-radiative broadenings of electronic excitations.
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Light reflection and absorption spectra by a semiconductor quantum well (QW), which width is comparable to a light wave length of stimulating radiation, are calculated. A resonance with two close located exited levels is considered. These levels can
arise due to splitting of an energy level of an electron-hole pair (EHP) due to magnetopolaron effect, if the QW is in a quantizing magnetic field directed perpendicularly to the QW plane. It is shown that unlike a case of narrow QWs light reflection and absorption depend on a QW width $d$. The theory is applicable at any ratio of radiative and non-radiative broadenings of electronic excitations.
Reflectance, transmittance and absorbance of a symmetric light pulse, the carrying frequency of which is close to the frequency of interband transitions in a quantum well, are calculated. Energy levels of the quantum well are assumed discrete, and tw
o closely located excited levels are taken into account. A wide quantum well (the width of which is comparable to the length of the light wave, corresponding to the pulse carrying frequency) is considered, and the dependance of the interband matrix element of the momentum operator on the light wave vector is taken into account. Refractive indices of barriers and quantum well are assumed equal each other. The problem is solved for an arbitrary ratio of radiative and nonradiative lifetimes of electronic excitations. It is shown that the spatial dispersion essentially affects the shapes of reflected and transmitted pulses. The largest changes occur when the radiative broadening is close to the difference of frequencies of interband transitions taken into account.
The cross section of light absorption by semiconductor quantum dots in the case of the resonance with excitons $Gamma_6 times Gamma_7$ in cubical crystals $T_d$ is calculated. It is shown that an interference of stimulating and induced electric and m
agnetic fields must be taken into account. The absorption section is proportional to the exciton nonradiative damping $gamma$.
Tunnel spectroscopy is used to probe the electronic structure in GaAs quantum well of resonant tunnel junction over wide range of energies and magnetic fields normal to layers. Spin degenerated high Landau levels ($N=2div7$) are found to be drastical
ly renormalised near energies when the longitudinal optical-phonon ($hbaromega_{LO}$) and cyclotron energy ($hbaromega_{C}$) are satisfied condition $hbaromega_{LO}=mhbaromega_{C}$, where $m=1,2,3$. This renormalisation is attributed to formation of resonant magnetopolarons, i.e. mixing of high index Landau levels by strong interaction of electrons at Landau level states with LO-phonons.
We propose a lateral spin-blockade device that uses an InGaAs/InAlAs double quantum well (DQW), where the values of the Rashba spin-orbit parameter $alpha_{rm R}$ are opposite in sign but equal in magnitude between the constituent quantum wells (QW).
By tuning the channel length of DQW and the magnitude of the externally applied in-plane magnetic field, one can block the transmission of one spin (e.g., spin-down) component, leading to a spin-polarized current. Such a spin-blocking effect, brought about by wave vector matching of the spin-split Fermi surfaces between the two QWs, paves the way for a new scheme of spin-polarized electric current generation for future spintronics applications based on semiconductor band engineering.
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