Zener tunneling effect of excitons in shallow superlattices

Abstract

The Zener effect in the optical absorption of shallow superlattices is studied theoretically and experimentally. The comparison between the Kane approximation, which is the widely accepted picture so far, and a numerical calculation including all subbands, provides clear evidence for the Zener effect. The experimental spectra are in good agreement with the theory. The measured line broadening as a function of the electric field behaves as predicted by the Zener theory, and is of the same order of magnitude as calculated from the sample parameters. We also suggest absorption measurements in a magnetic field in growth direction, which would provide an even clearer demonstration for the transition between discrete transitions and the continuum due to Zener tunneling.

Spectral modulation of exciton Fano resonance due to Zener breakdown in strongly biased superlattices

“…It would be expected from the results of the spectrum of the 0͑1, 1͒ state in Ref. 27, that the stronger Zener breakdown broadens the spectral width. However, as far as the F ഛ 110 kV/ cm region is concerned, the linewidth broadening is not pronounced yet for every FR spectrum of Fig.…”

“…[21][22][23][24] Moreover, the transitions into continuum states in strongly coupled WSL were also observed by infrared spectroscopy, 25 and were theoretically investigated in comparison with the Kane approximation. [26][27][28] In addition, the Bloch oscillation damped by the Zener breakdown that was associated with linewidth broadening due to field-induced delocalization was observed using the time-resolved measurement. 29 On the other hand, the Zener resonance was studied by the analysis of the photocurrent-voltage characteristics and photoluminescence spectroscopy by addressing the connection with the electric field domain formation, 30,31 and through dc and microwave transport experiments.…”

“…17 The effects of the Zener breakdown under a relatively strong bias on the WSL spectra and nonlinear transport, ͑i.e., the Bloch oscillation͒ resulting in negative differential resistance ͑NDR͒, were later discussed by many authors. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Hereafter, the resonant Zener tunneling between different energetically aligned subbands will be termed as Zener resonance or WSL resonance. Delocalized electron states in coupled WSL in biased SLs were first observed by photocurrent spectroscopy along with the measurement of the currentvoltage characteristics by Schneider et al 18 They observed the delocalization of electrons and anticrossing behavior ascribable to the nearest-and the second-nearest-neighbor resonant couplings induced by the Zener resonance.…”

Influence of a strong magnetic field on the Wannier-Stark states of an electrically biasedGaAs/AlxHummel1, Bauer2, Roskos3 et al. 2003Phys. Rev. BSelf Cite8050View full textAdd to dashboardCite

“…The matrix elements of the exciton Hamiltonian in the basis of Wannier functions are given in Ref. 13.…”

“…More recent developments include spontaneous emission from Wannier-Stark ladders, 11 control of wave packets by ac and dc fields, 12 and the Zener breakdown in superlattices. 13 In the last decade, much work has been done on the effects of an additional magnetic field on the optical 14 -34 and transport [35][36][37][38][39] properties of semiconductor quantum wells and superlattices. A ͑sufficiently strong͒ magnetic field applied perpendicularly to the quantum-well layers ͑Faraday geometry͒ quantizes the motion of the carriers in the layer plane and reduces the dimensionality of the semiconductor.…”