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We report an electrical transport and electroluminescence (EL) spectroscopy study of single-barrier GaAs-AlAs-GaAs $p\ensuremath{-}i\ensuremath{-}n$ tunnel structures with a barrier thickness in the range 4.5--8.0 nm. The results permit us to determine directly the relative roles of nonresonant \ensuremath{\Gamma}-\ensuremath{\Gamma} tunneling and resonant $\ensuremath{\Gamma}\ensuremath{-}X\ensuremath{-}\ensuremath{\Gamma}$ intervalley transfer in the transport through the indirect-gap tunnel barriers. The $\ensuremath{\Gamma}\ensuremath{-}X\ensuremath{-}\ensuremath{\Gamma}$ transport is shown to take place predominantly without conservation of transverse wave vector ${(k}_{\ensuremath{\parallel}}),$ with ${k}_{\ensuremath{\parallel}}$-conserving scattering via ${X}_{z}$ states only significantly close to the onset of $\ensuremath{\Gamma}\ensuremath{-}X$ intervalley transfer. By detecting extremely weak EL arising from excited ${X}_{z}$ states we show that the complete $\ensuremath{\Gamma}\ensuremath{-}X\ensuremath{-}\ensuremath{\Gamma}$ transport process is very strongly sequential and determine, quantitatively, the comparative time scales for $X\ensuremath{-}\ensuremath{\Gamma}$ and inter-X-level scattering. The bias-dependent $\ensuremath{\Gamma}\ensuremath{-}X\ensuremath{-}\ensuremath{\Gamma}$ and \ensuremath{\Gamma}-\ensuremath{\Gamma} transport times are determined for AlAs barrier widths in the range 3.0--10 nm. The intervalley $\ensuremath{\Gamma}\ensuremath{-}X\ensuremath{-}\ensuremath{\Gamma}$ transport model yields results in good agreement with experiment and demonstrates that, providing intervalley $\ensuremath{\Gamma}\ensuremath{-}X$ transfer is energetically possible, nonresonant \ensuremath{\Gamma}-\ensuremath{\Gamma} tunneling only contributes significantly to the transport characteristics for barrier widths of \ensuremath{\sim}3 nm or less.

The quantum efficiency of an electroluminescent intersubband emitter based on $\mathrm{In}\mathrm{As}∕\mathrm{Al}\mathrm{Sb}$ has been measured as a function of the magnetic field up to $20\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. Two series of oscillations periodic in $1∕B$ are observed, corresponding to the elastic and inelastic scattering of electrons of the upper state of the radiative transitions. Experimental results are accurately reproduced by a calculation of the excited-state lifetime as a function of the applied magnetic field. The interpretation of these data gives an exact measure of the relative weight of the scattering mechanisms and allows the extraction of material parameters such as the energy-dependent electron effective mass and the optical phonon energy.

The inelastic scattering rates of electrically injected minority hot electrons measured using a continuous-wave spatially resolved electroluminescence spectroscopy are reported. To our knowledge, this constitutes direct experimental determination of this parameter related to the individual inelastic interactions. The evolution of the electron relaxation rate with increasing majority hole density is explored. Remarkably, an attenuation of the scattering rate is measured for p-doping levels higher than $2\ifmmode\times\else\texttimes\fi{}{10}^{19} {\mathrm{cm}}^{\ensuremath{-}3}.$ Additionally, the measured hot-electron energy distributions further indicate that the relaxation mechanisms are dominated by LO phonon-plasmons coupled modes in the range ${10}^{18}$ to ${10}^{19} {\mathrm{cm}}^{\ensuremath{-}3}$ hole density. Finally, the temperature dependence of inelastic scattering rate is also measured to learn on the potential implication of ballistic transport in RT operating hot-electron devices.

Complex photonic band structures (CPBS) of transmission metallic gratings with rectangular slits are shown to exhibit strong discontinuities that are not evidenced in the usual energetic band structures. These discontinuities are located on Wood's anomalies and reveal unambiguously two different types of resonances, which are identified as horizontal and vertical surface-plasmon resonances. Spectral position and width of peaks in the transmission spectrum can be directly extracted from CPBS for both kinds of resonances., 4 pages, 4 figures, REVTeX version 3