A comparative study of the carrier distributions in dynamically operating GTO's by means of two optically probed measurement methods

Abstract

Two optical scanning techniques are employed for the measurement of local carrier concentration in power devices. 3-D type maps of two-dimensional carrier distri- butions are produced. The time resolution of the instruments facilitates measurements of the transient phases of device operation. The instruments are well suited for the characte- rization of any device, ranging from simple diodes to GTO:s, provided that the samples are small in geometry, and properly prepar- ed. This investigation compares the methods as regards differences in detection principles, sensitivity, and applicability.