Internal infrared laser deflection system: a tool for power device characterization

Abstract

In this paper, a set-up based on the internal IR-laser deflection technique is described. This technique allows measurement of the temperature gradient and free-carrier concentration inside power semiconductor devices with high spatial (35 µm) and time (less than 1 µs) resolution. The internal IR-laser deflection technique consists in the measurement of deflection and absorption of an IR-laser beam passing through a biased power device. After describing the operational principle and the experimental set-up, the postprocessing methodology followed to extract the temperature gradient and free-carrier concentration is detailed. In order to show the set-up functionality, the drift region of a 600 V PT-IGBT device has been studied. These measurements are very helpful for performing reliability or thermal management studies on power semiconductor devices.