New microwave techniques for observing dynamic plasma spread in thyristors

Various characteristics of semiconductor devices are determined by the behavior of the injected carrier. Thus, it is desirable to measure the spatial distribution of the injected carrier density and its time variation. This paper describes a new microwave technique for the measurement of conductivity in a small portion of a semiconductor. The new technique uses a special antenna by which microwaves are radiated onto a small surface area and the reflected microwaves from this surface are received. The new technique has the advantage that excess carrier density and current density at a small area (0.01 ∼ 0.1 mm²) in semiconductor devices can be determined.