Maxime Forster

Influence of net doping, excess carrier density and annealing on the boron oxygen related defect density in compensated n-type silicon

In this study, we present experimental data regarding the concentration of the boron-oxygen complex in compensated n-type silicon when subjected to illumination. We find that the defect density is independent of the net dopant concentration and is strongly dependent on the minority carrier concentration during illumination. We show that annealing at temperatures in the range 500 � C to 700 � C permanently reduces the defect density possibly via a decrease in the oxygen dimer concentration. V C 2011 American Institute of Physics. [doi:10.1063/1.3633492]

Boron-oxygen defect in Czochralski-silicon co-doped with gallium and boron

We study the boron-oxygen defect in Si co-doped with gallium and boron with the hole density 10 times higher than the boron concentration. Instead of the linear dependence of the defect density on the hole density observed in boron and phosphorus compensated silicon, we find a proportionality to the boron concentration. This indicates the participation of substitutional, rather than interstitial, boron in the defect complex. The measured defect formation rate constant is

Impact of incomplete ionization of dopants on the electrical properties of compensated p-type silicon

This paper investigates the importance of incomplete ionization of dopants in compensated p-type Si and its impact on the majority-carrier density and mobility and thus on the resistivity. Both theoretical calculations and temperature-dependent Hall-effect measurements demonstrate that the carrier density is more strongly affected by incomplete ionization in compensated Si than in uncompensated Si with the same net doping. The previously suggested existence of a compensation-specific scattering mechanism to explain the reduction of mobility in compensated Si is shown not to be consistent with the T-dependence of the measured carrier mobility. The experiment also shows that, in the vicinity of 300 K, the resistivity of compensated Si has a much weaker dependence on temperature than that of uncompensated silicon.

Recombination Activity and Impact of the Boron–Oxygen-Related Defect in Compensated N-Type Silicon

In this paper, we present experimental data regarding the recombination activity and concentration of the boron-oxygen complex in compensated n-type silicon, doped with phosphorus and boron, when subjected to illumination. Unlike the data of Bothe in n-type silicon compensated with thermal donors, our results suggest the dominant defect level in our doping range to be a shallow level (EC- ET = 0.15 eV), with a capture cross-section ratio σn /σp of around 0.006, suggesting a negatively charged center. We also confirm previous results showing an increasing defect density with bias light intensity. Due to the strong lifetime reduction observed, we suggest that this material might not be suited to make high-efficiency n-type solar cells, unless practical strategies to reduce the defect concentration can be developed.

Incomplete Ionization and Carrier Mobility in Compensated p -Type and n-Type Silicon

In this paper, we show through both calculations and Hall effect measurements that incomplete ionization of dopants has a greater influence on the majority-carrier density in p-type and n-type compensated Si than in uncompensated Si with the same net doping. The factors influencing incomplete ionization at room temperature are shown to be the majority-dopant concentration, its ionization energy and type, and the compensation level. We show that both the majority- and the minority-carrier mobilities are lower in compensated Si than expected by Klaassens model and that the discrepancy increases with the compensation level at room temperature. The study of the temperature dependence of themajority-carrier mobility shows that there is no compensation-specific mechanism and that the reduction of the screening in compensated Si cannot explain alone the observed gap between experimental and theoretical mobility.