Deuterium (hydrogen) incorporation in dilute nitrides (e.g., GaAsN and GaPN) modifies dramatically the crystal's electronic and structural properties and represents a prominent example of defect engineering in semiconductors. However, the microscopic origin of D-related effects is still an experimentally unresolved issue. In this paper, we used nuclear reaction analyses and/or channeling, high resolution x-ray diffraction, photoluminescence, and x-ray absorption fine structure measurements to determine how the stoichiometric [D]∕[N] ratio and the local structure of the N-D complexes parallel the evolution of the GaAsN electronic and strain properties upon irradiation and controlled removal of D. The experimental results provide the following picture: (i) Upon deuteration, nitrogen-deuterium complexes form with [D]∕[N]=3, leading to a neutralization of the N electronic effects in GaAs and to a strain reversal (from tensile to compressive) of the N-containing layer. (ii) A moderate annealing at 250 °C gives [D]∕[N]=2 and removes the compressive strain, therefore the lattice parameter approaches that of the N-free alloy, whereas the N-induced electronic properties are still passivated. (iii) Finally, annealings at higher temperature (330 °C) dissolve the deuterium-nitrogen complexes, and consequently the electronic properties and the tensile strain of the as-grown GaAsN lattice are recovered. Therefore, we conclude that the complex responsible for N passivation contains two deuterium atoms per nitrogen atom, while strain reversal in deuterated GaAsN is due to a complex with a third, less tightly bound deuterium atom.
Dilute nitride based double-barrier quantum-well infrared photodetector operating in the near infrared
Near-infrared detection is reported for a double-barrier quantum-well infrared photodetector based on a 30-Å GaAs1−yNy (y ≈ 0.01) quantum well. The growth procedure using plasma-assisted molecular-beam epitaxy is described. The as-grown sample exhibits a detection wavelength of 1.64 μm at 25 K. The detection peak strengthens and redshifts to 1.67 μm following rapid thermal annealing at 850 °C for 30 s. The detection peak position is consistent with the calculated band structure based on the band-anticrossing model for nitrogen incorporation into GaAs
Terahertz response of hot electrons in dilute nitride Ga(AsN) alloys
We model theoretically an unusual ac negative differential mobility (NDM) effect that occurs when electrons are accelerated by an electric field in the highly nonparabolic conduction band of dilute nitride Ga(AsN) alloys. By solving balance equations that take into account the negative effective mass of electrons and the velocity and energy relaxation processes, we derive an expression for the maximum response frequency, fmax, associated with the NDM. Our predicted values of fmax depend on material composition and can be tuned by the applied electric field up to terahertz frequencies
Modeling of band gap properties of GaInNP alloys lattice matched to GaAs
Compositional and temperature dependences of the band gap energies of GaInNP alloys, which are lattice matched to GaAs, are determined and modeled by a band anticrossing (BAC) interaction between the localized state of the isolated NP and extended host states. The BAC parameters are deduced as EN = 2.1±0.1 eV and CMN = 1.7±0.2 eV. The low value of the coupling parameter CMN implies weaker coupling of the N level with the host matrix, presumably due to short range ordering effects, similar to the case of GaInNAs alloys with a high In content. The obtained information is important for future modeling of the electronic structure of the alloys
ROSSANA HERNANDEZ
electronica del estado solido
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