METHOD FOR DETERMINING THE RECOMBINATION RATE OF MINORITY CARRIERS AT BOUNDARY SURFACES BETWEEN SEMICONDUCTORS AND OTHER SUBSTANCES

摘要

For a two-stage measuring method, a respective cell having an electrode therein is applied to the front surface and to the rear surface of a semiconductor wafer, whereby only the cell as the rear surface is filled with an electrolyte in the first measuring step. The minority carrier photo current I2' flowing between the electrode and the semiconductor surface in the rear cell, given illumination of the front cell of the semiconductor crystal wafer, is dependent on the recombination speed S at the front surface. In the second measuring step, the front cell is also filled with electrolyte and both the rear surface photo current I2, given what is now a negligible influence of the value S as well as the front surface photo current I1 are measured. The recombination speed S can be calculated from the measure photo currents with the assistance of a mathematical equation. Given point-by-point illumination and scanning over the crystal wafer, the topical distribution of the recombination speed is obtained.