Abstracts of Bell System Technical Papers Not Published in This Journal (01 May 1952)

To account for the non-uniformities in the electrical properties of diamond, particularly those observed in bombardment conduction, the proposal is made that the well-known lattice imperfections are not distributed homogeneously in the physical crystal, and that the resulting fluctuations in the height of the energy bands relative to the Fermi level might produce interspersed "pools of mobile charge" separated by barriers within the diamond. These pools and barriers should lead to dielectric losses at high frequencies. 

A single conducting channel, in series with a barrier, could be represented by a series resistance R, and capacity C, or by the equivalent parallel resistance R p and capacity C p . With some, but not all, diamonds measurable dielectric losses at 70 mc/sec were observed. RP varied from 5 X 10® ohms, the limit of measurement, to 4 X 106 ohms. Furthermore, the proposed model suggests that, in some cases, these barriers might be sufficiently lowered to establish a dc conducting channel all the way through a crystal. With a few of the lossy diamonds precisely this phenomenon of "high conduction" has been observed, in which a resistance of the order of a megohm is obtained with a dc voltage applied. This current appears abruptly in time but it lags behind the application of the voltage.

This lag is influenced by irradiation with light or alpha-particles or by previous treatment. T h e proposed pools of mobile charge are a sufficient but not necessary description of the dielectric loss observations, but the high conduction phenomenon lends further support to this idea of conducting channels with barriers in lossy diamonds.