A New Microwave Method for Testing Nonlinear Effects in Solids

A new very sensitive method was developped for testing nonlinear effects in solids. Basic components of the measuring system are: Two microwave signal sources, a multimode cylindrical cavity and a superheterodyne receiver. The Q of the cavity loaded with the sample under test is monitored at one microwave frequency. This Q may be changed (modulated), when another electromagnetic field is switched-on at the second frequency corresponding to another cavity mode. The method is especially suitable for measuring strain-sensitive materials. No contacts are used to the sample. Typical applications are warm and hot electron effects in semiconductors. K-u band apparatus is described. The method is used by the authors for the determination of the flow of the energy from the inverted spins of the conduction electrons in InSb to the orbital degree of freedom.