Microwave techniques in the study of semiconductors

Application of microwave techniques to the study of semiconductors is steadily gaining importance for various reasons. This paper describes some microwave methods for the measurement of semiconductor parameters developed at the Institute of Radio Physics and Electronics, University of Calcutta, India. The theory of conduction in semiconductors at microwave frequencies is first reviewed briefly. A SWR method is then outlined and its application to the study of temperature variation of conductivity and dielectric constant is discussed. An experimental arrangement for the measurement of surface conductance utilizing the above method is also described. A technique for the measurement of infrared absorption coefficient of a semiconductor is then presented and the experimental results obtained with a p-type silicon sample are given. The paper concludes with a description of two different methods developed for measuring the minority carrier lifetime. The possibility of utilizing one of these methods for obtaining the diffusion length, diffusion constant and surface recombination velocity in addition to lifetime, is also indicated.