Enhanced multiphonon capture of hot electrons by deep centers with strong lattice coupling:: A Monte Carlo study of InP:Fe

The free-carrier energy dependence of the nonradiative multiphonon capture mechanism in semiconductors is investigated in the case of weak and strong lattice coupling of the deep center, considering high and low lattice temperatures. It is shown that in the case of strong coupling, the multiphonon capture probability is resonantly enhanced for hot electrons. This effect is even more pronounced at low temperatures. Consequently, enhanced capture of hot electrons by DX or other deep centers can be explained in a very general way. Incorporating the analytically calculated energy dependent multiphonon capture probability into a Monte Carlo transport simulation of InP, the electric field dependence of the effective electron capture cross section is calculated. By varying the Huang-Rhys coupling constant over a wide range of magnitude, the cases of weak and strong electron-lattice interaction are investigated. For strong coupling, an enhancement of the capture cross section in the presence of a high electric field is found, in accordance with the experimental data for Fe-doped InP. By attributing the capture of electrons to the excited state Fe2+(T-5(2)), excellent agreement is obtained between the theoretical calculation and the experimental data for both the: temperature and the electric field dependence of the capture cross section. The calculated temperature dependence reveals a lowering of the capture barrier induced by the electric field.