Plasma wave instability in the conditions of the intervalley transition

Abstract

Abstract It is shown that plasma wave instability occurs when the transition from the low valley with light electron mass to the upper valley with heavy mass takes place (as in GaAs). The threshold of this instability is lower than the threshold of the Gunn effect if ωpo τ1 ⪡1 where ωpo is the plasma frequency of electrons in the absence of the electric field, τ1 is the impulse relaxation time of electrons (for GaAs this condition fulfills for no >nocr = 2.5 × 1015cm-13). This instability changes the conventional picture of the Gunn effect for no >nocr. In this case first of all the amplitude of the plasma waves begins to increase. Besides GaAs the instability may occur in other semiconductors including those where the Gunn effect is absent but the intervalley transitions takes place during the time less than the impulse relaxation time.