Light-induced degradation in compensated p- and n-type Czochralski silicon wafers

Light-induced degradation (LID) due to boron-oxygen complex formation seriously diminishes the minority carrier lifetime of p-type Czochralski-grown (Cz) wafers. Depending linearly on the boron concentration N-A in uncompensated silicon, the boron-oxygen defect density was suggested to depend on the net doping concentration p(0) = N-A - N-D in compensated p-type samples, containing similar amounts of boron and phosphorus [D. Macdonald, F. Rougieux, A. Cuevas, et al., Journal of Applied Physics 105, 093704 (2009)]. However, this dependency contradicts observations of LID in compensated n-type silicon wafers [T. Schutz-Kuchly, J. Veirman, S. Dubois, et al., Applied Physics Letters 96, 1 (2010)], which are confirmed in this study by investigating the boron-oxygen complex formation on a large variety of compensated p- and n-type samples. In spite of their high boron content, compensated n-type samples may show a less pronounced LID than p-type samples containing less boron. Our experiments indicate that in compensated silicon, the defect concentration is only a function of the compensation ratio R-C = (N-A + N-D)/(N-A - N-D). (C) 2011 American Institute of Physics. [doi:10.1063/1.3552302]