Evaluation of fast turn-on characteristics of power devices by IR-laser probing technique

Summary form only given, as follows. The IR-laser probing technique was used for evaluating the ultimate performance of the semiconductor power devices operated in fast-pulsed operation. Recently, the power devices are widely used as primary switches in the pulsed power sources, where the turn-on characteristics are much important than the turn-off characteristics. However, the externally measured characteristics such as voltage falling time, turn-on delay time, di/dt, switching power loss, etc., are not adequate for evaluating the maximum performance of those characteristics. Therefore, the measurement of the carrier distribution during the turn-on phase should be quite useful to study such characteristics. We used a contactless probing technique developed to measure the carrier concentrations within the power devices. The sample used in the experiment was one segment of a power device. The segment was mounted within a fast driving circuit that had extremely low residual inductance. The infrared laser beam of 1.3 /spl mu/m or 1.5 /spl mu/m wavelength emitted from a laser diode was focused on the one side of the segment. Because of the small size of focusing spot, this system allows the measurement of carrier concentration with high spatial resolution. The measured carrier distribution was also compared with the simulation results obtained by a 2D device simulator.