The magneto-resistance of p -type semiconducting diamond

Abstract

Measurements of the magneto-resistance at room temperature are described of three oriented semiconducting diamonds. The values obtained for Δ p/p 0 H 2 are: 2.66 x 10 -10 Oe -2 , 2.10 and 1.32 for the longitudinal effects in the [110], [100] and [111], respectively, and range from (2.79 to 6.80) x 10- 10 for the various transverse effects. The components of the magneto-conductive tensor have been determined from these measurements. The results are compared with calculations carried out for a triply degenerate valence band, assuming that the energy surfaces can be approximated to by two warped spheres and one sphere. These computations are an extension of the two band calculations carried out by Mavroides & Lax (1957) for germanium. In the approximation described the band calculations of Herman (1953), Hall (1958) and Phillips (1958) have been used. The theoretical values of ∑ xxxx are within about 30% of the experimental values, but the predictions for ∑ xxyy and ∑ xyxy are lower than the values determined experimentally. The amount of warping, as indicated by the ratio ∑ xxxx / ∑ xxyy , required to account for the experimental values is less than that of the surfaces for which the calculations have been made. Thus the measured value of ∑ xxxx / ∑ xxyy is 0.51 ± 0.03 while the calculations give 0.80 (Herman), 0.91 (Phillips) and 1.26 (Hall).