MINORITY CARRIER TRANSPORT IN HEAVILY DOPED N-TYPE SILICON (EMITTERS, PHOSPHORUS EPITAXY, BIPOLAR TRANSISTOR, BANDGAP NARROWING, SOLAR CELL)

From first principles it is demonstrated that there are three hole transport and recombination parameters in heavily doped n-type silicon: the hole equilibrium concentration, the lifetime, and the diffusion coefficient. In steady-state, however, only two combinations of these three fundamental parameters are relevant: the hole equilibrium concentration - diffusion coefficient product, and the diffusion length. These two parameters have been measured in heavily phosphorus doped silicon fabricated by epitaxy.;For the measurement of the steady-state hole transport and recombination parameters, test structures with bipolar transistors have been fabricated. The diffusion length in the n('+)-epitaxial region is measured from the collector characteristics of identical p('++)-n('+)-p('++) lateral transistors with different base widths. Simultaneously, the equilibrium concentration - diffusion coefficient product is extracted from the collector characteristics of p('++)-n('+)-p vertical transistors. A doping range of two orders of magnitude has been covered. Previous steady-state measurements of the hole transport and recombination parameters from other authors have been reviewed. The original measurement of the two relevant parameters are reconstructed from the reported data. Agreement within a factor of two is obtained among all authors and this work.;Modelling of the current injected into heavily doped regions in steady-state is possible using only the two measured parameters. As illustration, the emitter saturation current of several bipolar transistors is predicted within 30% of the experimentally measured result, without any adjustable parameters.;Based on recent measurements of hole lifetime, values for the hole mobility and equilibrium hole concentration are obtained from the measured parameters. The hole mobility is found to be two times larger than its p-type silicon value. The equilibrium hole concentration is about a factor of two larger than predicted from values of bandgap narrowing measured by photoluminescence.;Good quality epitaxial layers were grown with doping levels up to 1.6 x 10('20) cm('-3). In the process of their characterization accurate measurements of electron mobility and Hall scattering factor were carried out.;Fits to the doping level dependence of the three fundamental hole transport and recombination parameters are computed that are suitable for device modelling.