Experimental Determination of Changes in Conductivity with Electric Field, Using a Stationary High-Field Domain Analysis

A method is described to determine experimentally the conductivity as a function of the actual electric field at high fields in the range of negative differential conductivity. For CdS doped with Ag and Al, it is shown that the conductivity decreases from about ${10}^{-7\mathrm{}}$ to below ${10}^{-10\mathrm{}}$ ${\mathrm{\Omega }}^{-1\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ at fields from 20 to 200 kV/cm. The experimental method is discussed by analyzing solutions of the Poisson and transport equations in terms of their projections in the $n-E$ plane, by following along the field of directions.