Free surface effect on the interaction of a two-dimensional electron gas with acoustic phonons in a quantizing magnetic field

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“…In this case the frequencies of the emitted phonons are close to the cyclotron frequency (ω ≈ ω B ) while the width of the frequency band is of the order of the cyclotron resonance line width, i.e. ∆ω ∼ 1/τ where τ is the momentum relaxation time [45]. This corresponds to the phonon wave packet attenuation length equal to sτ .…”

“…To illustrate the interface effect in quantizing magnetic fields, electron relaxation between discrete Landau levels in 2DEG located near free crystal surface has been studied [44,45]. The interface effect is obtained to be highest in the magnetic field since the 2DEG interacts with almost monochromatic cyclotron phonons in this case.…”

“…Optical phonons determine the character of electron relaxation at high temperatures and in various experiments with an optical excitation or Auger processes. In the 2DEG subjected to strong magnetic fields with rather thin electron layers and subjected to rather strong magnetic fields, a large separation between Landau levels cannot be covered by an acoustical LA phonon [45] so the multiphonon 2LA [47] or an optical phonon assisted [48] processes become more efficient. Longitudinal optical phonon assisted inter Landau level transitions via one-phonon emission mechanism requires a precise resonance.…”

“…In various recent experiments of light radiation [203,204,205] or Auger [55] processes in the QHE geometry, phonon emission remains the basic mechanism which ensures the relaxation of electrons firstly created in higher Landau states. However, in such effectively zero dimensional (0D) systems with rather thin electron layers and subjected to rather strong magnetic fields, a large separation between Landau levels cannot be covered by an acoustical LA phonon [45] so that the multiphonon 2LA phonon emission processes become more efficient [47]. Meanwhile an optical phonon emission requires a precise resonance ∆lω B = ω LO , ∆l = 1, 2, 3, • • • in this regime (ω B and ω LO are the cyclotron and the LO phonon frequencies).…”

“…The aim of the present chapter is to study theoretically the deformation acous- can be achieved for small values of ∆l = 1, 2, 3. On the other hand, acoustical phonon emission at electron transitions between such distant Landau levels is still a rather efficient effect [45,47,176] observable in experiment [203,204,205,55,56]. Numerical results are illustrated for PO phonon assisted relaxation between Landau levels l = 3 and l = 0.…”