THEORY OF NEGATIVE-MASS CYCLOTRON RESONANCE

It was recently suggested that the re-entrant energy contours of the heavy-hole bands in Ge and Si could contribute a negative resistivity component to the overall resistivity of these materials, possibly related to a non- equilibrium density of carriers in these re-entrant states. Such a phenomenon could be observed under cyclotron resonance conditions as an emission spectrum centered about the cyclotron frequency of these states, or as a reduction in the strength of the background absorption at that frequency. This idea is examined in detail, and it is found that except under very restrictive conditions, these states will in general add a normal, positive resistivity contribution to the material independently of their population. (W.D.M.)