Measurement of concentration and photoionization cross section of indium in silicon

Variable-temperature Hall-effect measurements, capacitance–voltage (C–V) measurements and flameless atomic absorption have been used to assess the concentration of indium in indium-doped silicon (Si:In) crystals. It was found that the flameless atomic absorption and C–V results were in very good agreement, but the extraction of an indium concentration from Hall-effect data was not a straightforward exercise due to the fact that the indium did not enter the ‘‘exhaustion’’ region. However, by analyzing the Hall data using a recent determination of the hole effective mass, and by using a physically reasonable value for the Hall scattering factor, the Hall data gave indium concentrations in very good agreement with the other two techniques. The Si:In substrates were also characterized optically using infrared absorption. These results, together with the indium concentrations determined above, yielded a peak indium photoionization cross section of (1.55±0.25)×10−16 cm2 at a 4-μm wavelength.