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The variation of the effective lifetime of minority carrier lifetime τeff with temperature has been studied in the temperature range 300–580 K in AlxGa1−xAs base regions of p+–p0–i–n0–n+ high-voltage GaAs–AlGaAs diodes grown by liquid-phase epitaxy. It was found by using deep level transient spectroscopy that the emission/capture of electrons and holes in AlxGa1−xAs p0–i–n0 epitaxial layers is governed by the DX− states of the DX center formed by Se/Te background impurities. The Arrhenius plots associated with the τeff were used to determine the activation energy of the hole capture to the DX− level to be Ec = 159 meV. It is shown that the thermal capture of holes to the DX− level determines the relaxation time of nonequilibrium carriers in the AlxGa1−xAs base layers as well as its temperature dependence. [ABSTRACT FROM AUTHOR]

A study of deep levels in InGaAs/GaAs and GaAsSb/GaAs p0–i–n0 heterostructures with misfit dislocations and identification of the effective defects responsible for the significant (by up to a factor of 100) decrease in the relaxation time of nonequilibrium carriers in the base layers (and in the related reverse recovery time) of InGaAs/GaAs and GaAsSb/GaAs high-voltage power p-i-n diodes is reported. Experimental capacitance–voltage characteristics and deep-level transient spectroscopy spectra of p+–p0–i–n0–n+ homostructures based on undoped GaAs layers without misfit dislocations and InGaAs/GaAs and GaAsSb/GaAs heterostructures with a homogeneous network of misfit dislocations, all grown by liquid-phase epitaxy, are analyzed. Acceptor defects with deep levels HL2 and HL5 are identified in GaAs epitaxial p0 and n0 layers. Dislocation-related electron and hole deep traps designated as ED1 and HD3 are detected in InGaAs/GaAs and GaAsSb/GaAs heterostructures. The effective recombination centers in the heterostructure layers, to which we attribute the substantial decrease in the relaxation time of nonequilibrium carriers in the base layers of p-i-n diodes, are dislocation-related hole traps that are similar to HD3 and have the following parameters: thermal activation energy Et = 845 meV, carrier capture cross-section σp = 1.33 × 10−12 cm2, concentration Nt = 3.80 × 1014 cm−3 for InGaAs/GaAs and Et = 848 meV, σp = 2.73 × 10−12 cm2, and Nt = 2.40 × 1014 cm−3 for the GaAsSb/GaAs heterostructure. The relaxation time of the concentration of nonequilibrium carriers in the presence of dislocation-related deep acceptor traps similar to HD3 was estimated to be 1.1 × 10−10 and 8.5 × 10−11 s for, respectively, the InGaAs/GaAs and GaAsSb/GaAs heterostructures and 8.9 × 10−7 s for the GaAs homostructure. These data correspond to the relaxation times of nonequilibrium carriers in the base layers of GaAs, InGaAs/GaAs, and GaAsSb/GaAs high-voltage power p-i-n diodes. [ABSTRACT FROM AUTHOR]

The effect of In and Al on the properties of the As[sub Ga] defect complex (arsenic substituted for gallium at a crystal lattice site) in GaAs-based quantum dots (QDs) was investigated using the nonempirical quantum-chemical SCF–MO–LCAO technique. It is shown that an As[sub Ga] defect can exist in stable and metastable states. Raising the indium or aluminum content in QD enhances the probability of As[sub Ga] defect formation in the stable state; in case of In introduction, this effect is manifested more strongly. The activation energy of the transition between stable and metastable states varies between 0.886 and 2.049 eV, depending on the QD stoichiometry. The formation of an As[sub Ga] defect gives rise to two deep levels in the band gap. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]