The influence of carrier injection on helical density waves

Abstract

In an injected plasma of a germanium crystal at 77 K the helical density waves setting in spontaneously or excited externally are investigated. The present work deals with externally excited density waves and compares the experimental results with the theory for a surface density wave. The composition of the plasma is influenced by changing the surface recombination rate, by a lateral p‐n junction, and by lateral illumination. This results in certain optimization demands for the amplification of the density waves. With regard to the problem of the current oscillations which are observed in the presence of helical density waves, an equivalent circuit is given which takes into account the resistance modulations by asymmetries of the density wave running out, and thus allows a better interpretation of the measured results.