An electrical technique for the measurement of the interface recombination velocity based on a three-terminal test structure

In this work, a novel test structure to measure the surface or interface recombination velocity is presented that can be used to measure the effect of different surface treatments made on an exposed surface after the test device has been fabricated. The test device is made by a vertical p+nn+ injecting diode, and by a floating n+ region, that acts as a sense terminal on the top surface. It can be shown that the voltage measured between the top floating terminal and the bottom, when the diode is forward biased, depends on the recombination velocity at surface. If this surface is exposed to subsequent processes (RIE etching, oxide deposition, etc.), the recombination properties of the new transition can be analysed. Two-dimensional simulations of the test structure operation have been performed, a variation of two orders of magnitude of the sense voltage is induced by varying S in the typical range of interest between 102 and 106 cm s−1, demonstrating the high sensitivity of the proposed method.