Contactless measurement of semiconductor conductivity by radio frequency‐free‐carrier power absorption

It is shown that, under suitable conditions, the power absorbed by a thin semiconductor slice in an oscillating magnetic field is accurately proportional to the material conductivity. The magnitude of this power absorption can be used to determine the conductivity by coupling the semiconductor to an amplitude‐stabilized marginal oscillator and noting the power needed to maintain the demanded level of oscillation. Instruments of this type have been constructed exhibiting ∼1% linearity over a 100:1 range of sample conductivity, a resolution of ∼1 in 104 and a limiting sensitivity of ∼10−5 mho/⧠. The method may be applied to the measurement of essentially any conducting material from semiconductors to metals.