Determining diffusion length of minority charge carriers - generating blocking space charge zone at semiconductor crystal wafer by applying voltage

摘要

An electrolyte permeated support is fitted to the back of the semiconductor crystal wafer. The latter is coupled to a voltage source via a contact between the water and an electrode in the electrolyte. Then the front side of the wafer is irradiated by light. A blocking space charge zone is generated on the rear side of the wafer by the applied voltage. By the illumination of the front side of the wafer a photo-current of the minority charge carriers is generated for measuring on the rear side. The diffusion length is determined by a specified equation, with photon flow detected by a calibrated photodiode. ADVANTAGE - Quantitative, local determination of diffusion length for wafer measuring.