A new type of oscillations in the transverse magnetoresistanee of nondegenerate semiconductors due to inelastic scattering of electrons by optical phonons was theoretically predicted by Gurevich and Firsov. 1 This new effect can be observed if the phonon spectrum of the crystal has an optical branch and if the magnetic field is sufficiently strong to satisfy the condition ftr = iiH/c = (erH/m*c)» 1, where Q is the cyclotron frequency, r is the electronic relaxation time, and ji is the electronic mobility. Later Efros 2 generalized the Gurevich-Firsov theory for degenerate statistics.The physical nature of these oscillations can be explained as follows. At very high magnetic field the distance between the adjacent Landau levels, HQ,, exceeds the longitudinal optical phonon energy, HQJ Q , and the probability of electron-phonon scattering is relatively small. When the magnetic field decreases, the Landau splitting energy H£l becomes equal to HOJ Q . Then the probability of electron-phonon scattering sharply increases, causing the p xx component of the resistivity tensor to increase (the magnetic field H is supposed to be oriented along the z axis).Further decrease of the magnetic field breaks the resonance condition, and the number of transitions induced by optical phonons is decreased until a new resonance is approached. The resonance condition is a> 0 = M£2, where M is an integer. Thus the part of the magnetoresistanee due to scattering by optical phonons should oscillate with a period A(l/#) =e/m*u> 0 c,
a)depending on the effective mass m* and co 0 .We have also investigated theoretically similar oscillations of the longitudinal magnetoresistanee for the case of low temperatures, where (fiw 0 /kT) 10 15 20 25 30 35 Kkgauss FIG.
We report on magnetic-field dependences of Hall coefficient and resistivity for InN films grown by plasma-assisted molecular beam epitaxy. The Hall coefficient rises with the magnetic field. This anomalous behavior is discussed in terms of the presence of highly conducting inhomogeneities in the films. According to the magnetic field and temperature dependences of the film resistivity, the inhomogeneities are attributed to metallic indium nanoparticles formed presumably around extended defects within the InN epilayers, at their surface and the InN/GaN interface. Good correlation is observed between the growth conditions of the InN films and their electrical properties recalculated using the model.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.