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Luminescent characteristics of asymmetric p-InAs/AlSb/InAsSb/AlSb/ p-GaSb type II heterostructures with deep quantum wells at the heterointerface are studied. The heterostructures were grown by metalorganic vapor phase epitaxy. Intense positive and negative luminescence was observed in the range of photon energies of 0.3–0.4 eV with a forward and reverse bias, respectively. Dependences of the spectra and intensities for positive and negative luminescence on the pumping current and on the temperature are studied in the range of 77–380 K. It is established that, at a temperature higher than 75°C, intensity of negative luminescence surpasses that of positive luminescence by 60%. The suggested heterostructures can be used as lightemitting diodes (photodiodes) with switched positive and negative luminescence in the mid-IR spectral range of 3–4 μm. [ABSTRACT FROM AUTHOR]

Electroluminescence bistability is observed in a typ-II P-AlGaAsSb/p-InGaAsSb/ N-AlGaAsSbheterostructure with lightly doped cladding layers and a narrow-gap active region (the width of the band gap is E[sub g]= 326 meV at the temperature T = 77 K). A currentcontrolled negative differential resistance is observed in the forward branch of the currentvoltage characteristic. Strong narrowband electroluminescence (half-width ∼ 7 - 10 meV) is observed at the end of the negative differential resistance interval, where the photon energy at the radiation maximum exceeds the width of the band gap of the narrow-gap material by 50 meV. This phenomenon is attributed to the tunneling injection and indirect radiative recombination of carriers localized at the AlGaAsSb/InGaAsSb heterojunction. As the voltage is increased, radiative transitions in the bulk of the active region begin to provide the main contribution, and the radiation maximum jumps to the long-wavelength end. Tunneling injection structures of this kind can be used to construct highly efficient current-controlled lightemitting diodes. [ABSTRACT FROM AUTHOR]

The electroluminescence of the single unconfined type-II heterojunction p-GaInAsSb/p-InAs was investigated in the temperature range T = 4.2-77 K. As the temperature was reduced below T = 77 K, the luminescence bands with maxima at 311 meV (band A) and 384 meV (band B) were found to shift toward higher energies. At 4.2 K, the short-wave band split into two bands, B[sub 1] and B[sub 2]. These results are explained in terms of a model involving recombinations of electrons from the conduction band to an acceptor level of InAs, and also recombinations of electrons and holes localized in self-consistent quantum wells on either side of the heterojunction. [ABSTRACT FROM AUTHOR]

The electroluminescence appearing upon pulsed excitation in a solitary p-GaInAsSb/p-InAs typeII (broken-gap) heterostructure is investigated at T = 77 K. It is shown that just as in the case of excitation by a constant current, two emission bands with maxima corresponding to 384 and 311 meV, respectively, are observed in the spectra. The half-widths of the emission bands equal 18-19 meV. Time-resolved spectroscopy is used to evaluate the relaxation time of the nonequilibrium carriers, which amounts to 6-7 µs. The emission spectrum is calculated on the basis of the Kane model, and the radiative recombination time is estimated. The theoretical estimates are in reasonable agreement with experiment. [ABSTRACT FROM AUTHOR]