Defect formation and diffusion in heavily doped semiconductors

The effect of high free-carrier concentrations on the formation of native defects is considered. It is shown that the onset of degenerate carrier statistics results in an abrupt reduction of the formation energy of charged native defects and an enhanced diffusion of impurities and host lattice atoms. The effects are especially important in very heavily doped semiconductors at reduced growth and processing temperatures. As an example, it is shown that the proper incorporation of the effects of the degenerate statistics is necessary for understanding the mechanisms determining the maximum attainable concentration of free carriers in p- and n-type ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As.