Scaling of band-gap reduction in heavily nitrogen doped GaAs

摘要: The band-gap reduction caused by heavy impurity doping in a semiconductor can be written as $\ensuremath{\delta}{E}_{g}(x)\ensuremath{\propto}{x}^{\ensuremath{\alpha}},$ where x is the mole fraction of impurities, and \ensuremath{\alpha} scaling exponent. It well known that $\ensuremath{\alpha}=1/3$ for n- or p-type (i.e., charged) doping, isolated center forms bound states. In contrast, incorporation isoelectronic impurities into commonly results alloy formation. this case, do not form any states (with small cluster sizes), one finds $\ensuremath{\alpha}=1.$ However, case nitrogen GaAs, although states, pairs do, we find $\ensuremath{\alpha}=2/3.$ rule revealed here demonstrates dominant mechanism large observed ${\mathrm{GaAs}}_{1\ensuremath{-}x}{\mathrm{N}}_{x}$ formation an band associated with pair