An apparatus for evaluating an associated semiconductor sample having two electrically distinct regions with a junction region disposed therebetween includes a laser for injecting carriers into a sample region, an electrical bias for impressing electrical fields on the sample, and a detector for detecting luminescence. A second laser is provided for injecting carriers into a second sample region opposite the first region. A method includes the steps of: optically generating carriers in a region, generating a drift field in the region that effectuates carrier drift toward the junction, and measuring the optical radiation generated by carrier recombination in the junction region. Preferably, the method also includes optically generating carriers in a second region and generating a drift field in the second region that effectuates carrier drift toward the junction. Typically, the two drift fields are generated together by applying voltage between the two regions.