New contactless method for lifetime measurement in semiconductor wafers

It has previously been demonstrated that a magnetic field caused by the photomagnetoelectric (PME) short-circuit current makes contactless measuring of recombination characteristics of a semiconductor wafer possible. In this paper, the general expression for the magnetic flux of this magnetic field is derived. The results are presented in graphical form showing magnetic flux as a function of absorption coefficient, bulk lifetime, and surface recombination velocity, with other wafer characteristics as parameters. The presented experimental results for germanium wafers are in agreement with the results calculated. A simple apparatus exploiting the method makes simple and rapid comparative measurement (with respect to a reference sample) of bulk lifetime as short as 10−7 s in wafers of arbitrary form possible. Lifetimes shorter than the one mentioned above can be measured under conditions discussed in the paper.