Theory of inelastic multiphonon scattering and carrier capture by defects in semiconductors: Application to capture cross sections
- Vanderbilt Univ., Nashville, TN (United States); University of Crete (Greece)
- Vanderbilt Univ., Nashville, TN (United States)
- Univ. of Florida, Gainesville, FL (United States)
- Vanderbilt Univ., Nashville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Inelastic scattering and carrier capture by defects in semiconductors are the primary causes of hot-electron-mediated degradation of power devices, which holds up their commercial development. At the same time, carrier capture is a major issue in the performance of solar cells and light-emitting diodes. A theory of nonradiative (multiphonon) inelastic scattering by defects, however, is nonexistent, while the theory for carrier capture by defects has had a long and arduous history. As such, we report the construction of a comprehensive theory of inelastic scattering by defects, with carrier capture being a special case. We distinguish between capture under thermal equilibrium conditions and capture under nonequilibrium conditions, e.g., in the presence of an electrical current or hot carriers where carriers undergo scattering by defects and are described by a mean free path. In the thermal-equilibrium case, capture is mediated by a nonadiabatic perturbation Hamiltonian, originally identified by Huang and Rhys and by Kubo, which is equal to linear electron-phonon coupling to first order. In the nonequilibrium case, we demonstrate that the primary capture mechanism is within the Born-Oppenheimer approximation (adiabatic transitions), with coupling to the defect potential inducing Franck-Condon electronic transitions, followed by multiphonon dissipation of the transition energy, while the nonadiabatic terms are of secondary importance (they scale with the inverse of the mass of typical atoms in the defect complex). We report first-principles density-functional-theory calculations of the capture cross section for a prototype defect using the projector-augmented wave, which allows us to employ all-electron wave functions. We adopt a Monte Carlo scheme to sample multiphonon configurations and obtain converged results. The theory and the results represent a foundation upon which to build engineering-level models for hot-electron degradation of power devices and the performance of solar cells and light-emitting diodes.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF) and Center for Nanophase Materials Science (CNMS)
- Sponsoring Organization:
- USDOE Office of Science (SC); Samsung Advanced Institute of Technology (SAIT); US Air Force Office of Scientific Research (AFOSR); National Science Foundation (NSF)
- Grant/Contract Number:
- AC05-00OR22725; ECCS-1508898; 316165
- OSTI ID:
- 1565494
- Alternate ID(s):
- OSTI ID: 1233869
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 92, Issue 21; ISSN 1098-0121
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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