Planar transmission line comprising a material having negative differential conductivity

A planar transmission line amplifier comprising;

• a Gunn semiconductor layer selected from the group consisting of gallium arsenide, indium phosphide, zinc telluride, cacmium telluride, indium arsenide under mechanical stress, and germanium at temperatures below 17.degree.K, said layer consisting of a substrate portion and an epitaxial portion, said epitaxial portion having a dopant concentration, n, from a surface of said epitaxial layer down to approximately 4 .mu.m from said surface and sharply decreases thereafter;
• at least two conductive plates ohmically contacting said epitaxial surface and being spaced to form a gap of width L therebetween, whereby the product n .sup.. L is less than 1 .times. 10.sup.12 atoms/cm.sup.2 ;
• an input port consisting of the first adjacent ends of said conductive plates, and output port consisting of the second, opposite, ends of said conductive plates;
• means for applying a voltage between said two conductive plates equal to a value sufficient to create an E field in the surface of said gap equal to approximately twice the Gunn threshold of said semiconductor layer;
• and means for applying an r.f. signal to said input port to cause said r.f. signal to propagate in a direction perpendicular to said E field vector.