Multiphonon carrier capture by defects in semiconductors

We report developments and corresponding calculations in the first-principles theory of multiphonon processes in solids, enabling direct calculations of nonradiative capture cross sections of both thermalized and hot carriers by defects in semiconductors. We present an improved derivation of the theory, implement an efficient time-domain integration scheme that enables summing over all possible multiphonon configurations for dissipating the energy released by the carrier capture, and extend the time-domain formulation to allow changes in phonon frequencies before and after capture. We examine zeroth- and first-order nonequilibrium contributions to the electron-capture cross section of a triply hydrogenated vacancy in Si and the first-order equilibrium hole-capture coefficient of a CN substitutional impurity in GaN. In Si, we find that the zeroth-order term is two orders of magnitude larger than the first-order term. In GaN, the present results are within range of the sparse available experimental data at high temperatures but below the single experimental point at low temperatures. We see an improvement over previous calculations and a decreased temperature dependence that we attribute to the inclusion of all phonon modes. locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon Physics Subject Headings (PhySH)DefectsElectrical conductivityFirst-principles calculationsPhonons