2-DIMENSIONAL ANALYSIS OF A TEST STRUCTURE FOR LIFETIME PROFILE MEASUREMENTS

A new electrical measurement technique has been proposed [1] that allo ws to obtain the ''local'' lifetime value in Si layers, by superposing ac measurements on a de bias in a three-terminal test structure, and hence to extract a lifetime ''profile'' along the depth of the layer b y varying the voltage bias. In this paper two-dimensional effects that could arise due to the lateral current how in the test structure are studied, and are related to the modifications of the lifetime profile extracted, Both a simplified analysis and 2-D simulations of the test structure behavior allow to explain the 2-D effects responsible for de viation of the lifetime profile from the correct one as dependent on t he geometry of the test structure, Moreover design rules are given for the test structure, that keep the error in the profile extracted with in safe limits.