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We investigate the nonlinear drift response of electrons in Si, GaAs, and InP crystals to high-power electromagnetic waves by means of a Monte Carlo technique, with the aim of developing an efficient frequency converter for 1 THz output radiation. Drift velocity amplitudes and phases determining the conversion efficiency are calculated for the first, third, and fifth harmonics in the pumping wave amplitude range of 10<E1<100 kV/cm, for frequencies between 30 and 500 GHz, and at the lattice temperatures of 80, 300, and 400 K. It is found that the efficiency is a maximum at the pumping wave amplitude of the order of 10 kV/cm depending on the intervalley electron scattering parameters and the lattice temperature. Cooling the nonlinear crystal down to the liquid-nitrogen temperature enhances the efficiency several times in Si and by orders of magnitude in GaAs and InP. This is promising for obtaining a 10% conversion efficiency.

Conventional models of electron transport in hexagonal GaN crystals predicting electron drift velocity peak value up to 3.2×107cm∕s at 140–220kV∕cm and a pronounced negative differential mobility at higher fields are revised. The new model is suggested accounting for the additional low-energy optical phonon modes (∼26meV) and the satellite valley location close (400meV) to the conduction band bottom. Electron scattering on these and conventional (∼92meV) LO-phonon modes together with the fast intervalley exchange is shown to limit electron drift velocity (<1.9×107cm∕s at T=300K), in excellent agreement with the time-of-flight experiment.

Photoluminescence of cleaved Cd 0.7 Mn 0.3 Te crystals is studied at T ≈ 1.6 K at the normal-and oblique (45 • ) incidence of the pumping Ar laser beam (λ = 488 nm) in magnetic fields −7 ≤ B ≤ 7 T in the Voigt geometry. At B = 0, photoluminescence maximum is found at 2.0819 eV at normal incidence (and backward emission) whereas the oblique incidence and emission shows photoluminescence maximum intensity at 2.0536 eV. The red shift of photoluminescence maximum position with the rise in B is observed and the results are found to be in good agreement with sp−d exchange interaction model for the oblique incidence case. Backward emitted photoluminescence line is found to narrow from 26.2 to 23.5 meV with the rise in B from 0 to 7 T. Alloy disorder contribution exhibits opposite trend to broaden, as is calculated on the basis of the matrix of the energy gap dependence on x and B. Therefore the observed photoluminescence line narrowing is assigned to the suppression of magnetic fluctuation in magnetic field. A linear size of magnetic fluctuation is estimated to be about 1/5 of the free exciton diameter. Photoluminescence maximum position difference in the normal-and oblique incidence cases is assigned to polaritons.

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