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A method for extracting the parameters of lmal levels from noise spectroscopic data for the case when the capture cross section of electrons an depends on temperature exponentially, an = mexp(-El/k7J, h a s been suggested. For the limiting cases when the Fermi level EF lies significantly below (EF -6 >> kT) or above (Eo -EF >> kT) the level 6, analytic expressions have been obtained to calculate ua, EO, El and the level concentration Nt. The results have been applied to noise-measurement data for GaAs samples with electron concentrations no * technique proposed can be applied to a wide variety of experimental situations.IOi6 and lO"~m-~. It has been shown that the

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The influence of the magnetic field on the excitation of plasma waves in InGaAs/AlInAs lattice matched high electron mobility transistors is reported. The threshold source-drain voltage of the excitation of the terahertz emission shifts to higher values under a magnetic field increasing from 0 to 6 T. We show that the main change of the emission threshold in relatively low magnetic fields (smaller than approximately 4 T) is due to the magnetoresistance of the ungated parts of the channel. In higher magnetic fields, the effect of the magnetic field on the gated region of the device becomes important. (C) 2005 American Institute of Physics

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It is demonstrated that, in addition to the well-known quasineutral modes of carrier transport, i.e., those of quasineutral diffusion and quasineutral drift, a quasineutral mode of diffusion stimulated by quasineutral drift (DSQD) is possible. An equation that describes this mode is derived and the principal specific features of the mode are examined analytically. In particular, an analytical expression for the current-voltage (I-V) characteristic is obtained for the case when just DSQD governs the carrier transport. The analytical results obtained are verified and confirmed by a detailed simulation.