Low‐Field Magnetoresistance and Magnetoconductivity in n‐Type Ge with Dislocations

Abstract

Expressions are derived for specified magnetoresistance and magneto-conductivity coefficients for n-type Ge with an array of parallel dislocations. The obtained equations are compared with measurements a t 77 O K on plastically bent n-type Ge. From the results we conclude that the electron mobility is not reduced by the dislocations for Ndw. <2 x lo7 cm-2.The observed anisotropies in the conductivity can be attributed to the inhomogeneous distribution of the dislocations.Es werden Ausdrucke fur bestimmte Magnetowiderstands-und Magnetoleitfiihigkeitakoeffizienten von n-leitendem Ge mit einer Anordnung paralleler Versetzungen abgeleitet. Die erhaltenen Gleichungen werden mit MeSergebnissen an plastisch gebogenem, n-leitendem Ge bei 77 O K verglichen. Aus den Ergebnissen wird geschlossen, da13 die Elektronenbeweglichkeit durch die Versetzungen nicht verkleinert wird, solange N&,l. < 2 x lo7 cm-2 ist. Beobachtete Anisotropien der Leitfiihigkeit konnen der inhomogenen Verteilung der Versetzungen zugeschrieben werden.

Transverse Magnetoresistance in Plastically Deformed n‐Type Germanium

“…From the calculated resistivity coefficients we obtained a mobility reduction at x = 10 of pH(x = 10)/(pH(x = 0) = 0.11. According to our measurements the Hall mobility of undeformed samples was about On the basis of their measurements, van Weeren et al [5] called attention to the fact that Broudy was erroneous when applying his own magnetoresistance measurements as a basis for a model of scattering by charged dislocations. Recently Schroter [I91 has called attention to the fact that up now the existence of rigid space cylinders around the dislocations was not proved unambiguously.…”

“…I n this case (for dislocation densities of the order of lo7 cm-2) R < I, and d = I, so the scattering model seems to be applicable. Van Weeren et al [5] have interpreted their magnetoresistance measurements on plastically deformed Ge on the basis of a phenomenological model taking into account the redistribution of the electric field around the dislocations. Contrary to our case they have not found a significant reduction in the mobility, so it is probable that the scattering effect of dislocations is negligible in their case.…”

“…Broudy [4] studied the angular dependence of magnetoresistance in plastically bent n-type germanium a t 77 O K . Van Weeren et al [ 5 ] have measured the magnetoresistance in plastically bent n-type germanium at 77 "K and found that dislocations with a density less than 2 x lo7 cm-2 have not significantly reduced the electron mobility. One of the authors of this paper [6] showed that dislocations generated by plastic deformation in n-type germanium influenced strongly the magnetoresistivity coefficients, and caused a strong violation of the symmetry relations between them.…”