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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]

We present the results of experimental studies of the capacitance–voltage (C–V) characteristics and the spectra of deep-level transient spectroscopy (DLTS) of graded high-voltage p+–p0–i–n0 GaAs diodes fabricated by liquid-phase epitaxy at a crystallization-onset temperatures of 900°C from one solution melt due to self doping with background impurities, in a hydrogen or argon atmosphere, before and after irradiation with neutrons. After irradiation with neutrons, the DLTS spectra reveal wide defect-cluster regions with acceptor-like negatively charged traps of the n0-type layer, resulting from the emission of electrons from states located above the middle of the band gap. It is found that the differences in the C–V characteristics of the structures grown in a hydrogen or argon atmosphere are due to the different doses of irradiation of p+–p0–i–n0 GaAs structures and different degrees of compensation of shallow donor impurities by deep traps in the layers. [ABSTRACT FROM AUTHOR]

Deep-level transient spectroscopy is used to study charge-carrier emission from the states of separate quantum dots in InAs/GaAs p–n heterostructures grown on (100)- and (311)A-oriented GaAs substrates in relation to the reverse-bias voltage U. It is established that the structures under consideration exhibit different bias-voltage dependences of the Stark shift for the energy levels of the quantum-dot states on the value of U. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

The results of a study of a structure with a single array of InAs quantum dots in a GaAs matrix using capacitance-voltage measurements, deep-level transient spectroscopy (DLTS), photoluminescence spectroscopy, and transmission electron microscopy are reported. Clusters of interacting bistable defects are discovered in GaAs layers grown at low temperature. Controllable and reversible metastable populating of quantum-dot energy states and monoenergetic surface states, which depends on the temperature and conditions of a preliminary isochronal anneal, is observed. This effect is associated with the presence of bistable traps with self-trapped holes. The DLTS measurements reveal variation of the energy for the thermal ionization of holes from surface states of the InAs/GaAs heterointerface and the wetting layer as the reverse bias voltage is increased. It is theorized that these changes are caused by the built-in electric field of a dipole, which can be formed either by wetting-layer holes or by ionized levels located near the heterointerface. [ABSTRACT FROM AUTHOR]

Deep-level transient spectroscopy was used to study the parameters of deep levels in the band gap of epitaxial n-GaN layers after irradiaton of the Schottky barriers with 1-MeV protons to a dose of 10[sup 12] cm[sup -2]. A deep level EP1 with an activation energy of 0.085 eV was introduced by irradiation into the upper half of the GaN band gap. The introduction rate of the corresponding defect was found to depend on the bias voltage applied to the Schottky barrier during irradiation. [ABSTRACT FROM AUTHOR]