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

The electrical conduction in an n-type In0.53Ga0.47As/InP sample grown by molecular beam epitaxy has been analyzed in the magnetic field up to 1.5 T, at temperatures from 15 to 295 K. The electrical conduction has been ascribed to the impurity band (IB), located in the interface between the epilayer InGaAs and the substrate InP. The contribution of the conduction band electrons in bulk InGaAs layer to the electrical conduction was negligible. The IB conduction was almost metallic. We observed within the IB two conducting channels which give positive and negative contribution to the Hall voltage. The magnetoresistance in the IB at low temperatures was negative, and at high temperatures was positive. The negative magnetoresistance in the IB has been phenomenologicaly described by carriers with the constant concentration and the mobility increasing proportionally to the square of the applied magnetic field.

No abstract