HELICON—DRIFT CURRENT INTERACTION IN A LAYERED SEMICONDUCTOR STRUCTURE

We have observed an interaction between helicon waves and drift currents in a layered lead telluride structure. In the low ωcτ regime of our experiments bulk wave effects are much greater than the surface wave interaction proposed by Baraff and Buchsbaum. Experiments performed on structures which have layers of equal dielectric constants and those with unequal dielectric constants both yield the same result; namely, the attenuation is reduced when the drift and wave propagate in the same direction and is increased when the two are in opposite directions. The observed interaction is strong and although spatial growth of the helicon waves has not yet been achieved with presently available drift velocities (Vdrift < Vphase), wave attenuation has been reduced by as much as 15 dB.