GaAs Luminescence Transitions to Acceptors in Magnetic Fields

Abstract

Low temperature luminescence spectra of pure and Sn-doped epitaxial GaAs are reported.

New aspects of the magnetoluminescence of a band to acceptor transition in GaAs

“…At small magnetic fields the position of the luminescence maximum is almost independent of the magnetic field, at higher fields again a linear shift is found. It might be interesting to note that these data look very similar to those published for the case of n-doped GaAs samples [2]. The solid line in Fig.…”

“…The magnetic field behaviour of the donor-acceptor pair recombination is well understood in principle : the magnetic field induced peak shift is governed by thediamagnetic shift of the donors and by the change of the so-called "Coulomb term" due to the shrinkage of the donor radius in a magnetic field [2]. However, for the peak shift of the (e, A") recombination remarkable discrepancies to the expected shift, which up to now was assumed to be the same as for the lowest Landau level of the conduction band (AE = + hw, = = (eh/m*c) H ) , were observed and could not be interpreted.…”

OPTICAL OBSERVATION OF THE MAGNETIC FREEZEOUT EFFECT IN GaSb

“…This shift should be doping independent. This has been verified for example in GaAs [7]. Not one of the lines investigated in GaSb show a linear shift at low fields and pronounced doping dependence has also been found in this region.…”

“…Only recently it was shown for the case of highpurity GaAs [7] that these transitions show a much more complex behaviour than believed before and one has to be very cautious before extracting detailed information from such experiments. In particular, effects of the banding of shallow impurities and of the screening of the binding potentials by free and bound carriers have been observed [7].…”

Inversion of Spin Photocurrent due to Resonant Transmission

“…Since the energy of feature X is closest to the energy band gap of GaAs (1.519 eV) at 10 K and the spectra for RCP and LCP components split well, we attribute the feature to the recombination of free excitons in the QW. Bulk-related emission, i.e., free exciton recombination X B , the conduction band to acceptor transition e-A 0 [5,17,18], and the LO phonon replica of X B , X B -LO [19], also occur in the GaAs buffer layer or substrate. Because the QW-related emission of X mainly contributes to the spin injection efficiency, we estimate the spin polarization of injected electrons by using P spin ¼ 2P circ , where P spin is the spin polarization of injected electrons and P circ is the circular polarization of the emitted light [20]: No clear trace of the splitting of the heavy hole (HH) level and the light hole (LH) level is seen, and the splitting is estimated to be $10 meV for our 20-nm-thick QW [1,2].…”