Maximum concentration of impurities in semiconductors

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Abstract
The electronic properties of impurities are shown to limit the attainable maximum impurity concentration in semiconductors. The repulsive interaction between impurities due to (i) the Coulombic charge of ionized impurities and (ii) the increase of electronic energy at high doping concentrations can result in impurity segregation effects that limit the maximum achievable doping concentration. As an example, we consider the doping properties of Be, C, and Zn in GaAs. The characteristics of these impurities at extremely high concentrations agree with Monte Carlo simulations and molecular-dynamics calculations of impurity incorporation during crystal growth, which take into account the repulsive interaction between impurities.