Crystal diodes

The first part of the paper gives the current views of the manner in which very small amounts of impurities give rise to the special electrical properties of semi-conductors, and of the mechanism of contact rectification. The preparation of germanium and silicon for use in crystal diodes is considered and the steps found necessary in the processing are discussed in terms of the theoretical ideas. In the second part of the paper, the design and performance of (a) a new coaxial-type silicon-crystal diode intended for use as a mixer at frequencies up to about 10 000 Mc/s, (b) a wire-ended germanium-crystal diode, are described and discussed. Particular attention is given to the frequency dependence of the rectification efficiency of the germanium diode, and its application as a replacement for the thermionic diode.