A problem of reconstruction of the radiation field in a domain Ω ⊂ R 3 from experimental data given on a part of boundary is considered. For the model problem described by a Cauchy problem for the Helmholtz equation, an approximate method based on regularization in the frequency space is analyzed. Convergence and stability are proved under a suitable choice of regularization parameter. Numerical implementation of the method is discussed.

A comprehensive investigation of the interfacial misfit (IMF) array formation has been carried out. The studies were based on the static phase diagram for GaAs (001) surface and As 2 dimers on the surface. Prior to the initiation of the GaSb growth two attempts of the temperature decreasing were performed: before and after the GaAs termination. The GaAs was grown in the optimal conditions for GaSb material. The influence of the interruption time on GaSb/GaAs heterostructure parameters was examined. Two cases were investigated: with and without Sb-soaking of the GaAs surface. The periodic array of edge dislocations at GaSb/GaAs interface was confirmed using Burger's circuit theory. Careful examination of misfit surroundings revealed one uncompleted Burger's vector that indicated one dislocation of mixed type among eight of the edge type. The distance between lattice sites of dislocations was 5.51 nm on average. The crystal quality of 5.0 µm GaSb layer was characterized by FWHM 2θ/ω = 42 arcsec, FWHM RC = 125 arcsec. The EPD = 4 × 10 6 cm − 2 was estimated after etching in FeCl 3 :HCl solution. The Δq z /Δq x ratio of 0.60 for 5.0 µm GaSb layer was higher than for 2.5 µm GaSb layer of 0.59. The probable reason was the thickness-dependent 60° dislocation density. The electrical parameters measured for 2.5 µm GaSb were: p = 4.0 × 10 16 cm −3 (2.0 × 10 16 cm −3 ) and µ = 599 cm 2 /V s (3420 cm 2 /V s) at 300 K (77 K).

We have set up a model for the energy-dependent lifetime, including the effects of the charge carrier collisions with ionized impurities, polar optical phonons, and space charge. The model is then used to compute the mobility spectrum at each temperature, which used to compute the pertinent magnetic-field-dependent Hall parameters. The computed Hall parameters compared can then be measured values to estimate the validity of the lifetime model and parameters. The method has been applied to two n-GaAs∕SI–GaAs epitaxial layers containing two types of carriers. The magnetic field dependence of the Hall voltage has been observed in the studied GaAs layers. We present the numerical solution of the neutrality equation, which contains all sources of charges present in the sample, and numerical integration of the total relaxation times ⟨τ⟩ so combined that is possible to obtain the mobility of the partial charges and their part in the whole conductivity of the layer.

No abstract

No abstract

No abstract

No abstract

Many-body effects have been optically investigated for modulation-doped quantum wells at high acceptor densities. The observed band-gap shrinkage, up to Ϸ20 meV, is consistent with calculations based on the Hartree and random-phase approximations including the finite well width effect. A recombination near the Fermi edge with light-hole character is strikingly enhanced at high acceptor densities. An interpretation based on carrier-carrier interaction is proposed. Finally, the exciton is found to be quenched for hole densities higher than Ϸ2ϫ10 12 cm Ϫ2 .