Dynamical Screening, Collective Excitations, and Electron‐Phonon Interaction in Heterostructures and Semiconductor Quantum Wells. Application to Double Heterostructures

Abstract

The collective excitations of a double heterostructure are examined in detail. Including the important effects of the interfaces of the system the uncoupled modes are analysed, which are the long-wave optical interface phonon modes, LO phonon modes, and intra-and intersubband plasmon modes. The electron-phonon interaction is discussed and the coupling functions are calculated and discussed in graphical form. The resulting coupled modes, intra-and intersubband plasmon-phonon modes, are calculated for different approximations of the polarization function, the random-phase approximation, the plasmon-pol approximation, and the long-wave approximation. The dispersion curves of these modes are presented in graphical form for various cases. It is shown that the Landau damping of the modes strongly depends on the layer thickness and the concentration of the quasi-two-dimensional electron gas.Die kollektiven Anregungen einer Doppelheterostruktur werden ausfuhrlich untersucht. Es werden die ungekoppelten Moden, d. h. die langwellig-optischen Grenzflachen-Phononen, die LO-Phononen sowie die Intra-und Intersubband-Plasmonen unter Einbeziehung der Grenzflacheneffekte diskutiert. Im Detail werden die Elektron-Phonon-Wechselwirkung analysiert, die Kopplungsfunktionen berechnet und graphisch dargestellt. Die resultierenden gekoppelten Moden, die Intraund Intersubband-Plasmon-Phononen werden fur mehrere Naherungen der Polarisationsfunktion, der Random-Phase-Approximation, der Plasmon-Pol-Naherung und der langwelligen Naherung berechnet. Die Dispersionskurven sind fur verschiedene Falle graphisch dargestellt. Es wird gezeigt, daB die Landau-Dampfung der Moden stark von der Schichtdicke und der Konzentration des quasi-zweidimensionalen Elektronengases abhangt.

Temperature changes in the function of the shape inherent to the band of exciton absorption in nanofilm of layered semiconductor

“…The Hamiltonians for free phonons and electronphonon interaction in double heterostructures (in coordinate representation by electron variables) were obtained in [18,19]. In the case of the system studied here, the former acquires the following look:…”

“…where Ω LO is the energy of longitudinal optical (LO) polarization phonons confined in QW medium; The Hamiltonian for EPI [18,19] expressed by the authors of [13] in the secondary quantization representation by all the variables of this electron-phonon system is as follows:…”

Temperature changes of the exciton transition energy in lead di-iodide nanofilms

“…As usual, theoretical investigations of semiconductor nano-heterostructures are performed in the approach of effective masses for the electron subsystem and within the model of dielectric continuum -for the phonon one [17][18][19] …”

“…The Hamiltonians for free phonons and excitonphonon interaction (EPI) (in coordinate representation by electron variables) have been obtained in the works [17,18]. For the system under consideration, the former takes the following look:…”

“…Here, The Hamiltonian for exciton-phonon interaction (EPI) [17,18] used by the authors of [22] before representation within the framework of secondary quantization by all the variables of the electron-phonon system…”