Lattice strain controls the carrier relaxation dynamics in Cd_xZn_1-xS alloy quantum dots

Abstract

Here, we demonstrate the impact of lattice strain on the carrier relaxation of Cd_xZn_1-xS alloy nanocrystals. In alloy nanocrystals, the difference in the lattice constants of their constituents can induce a lattice strain that varies with the composition of alloy. We have analyzed the decay curves using a multiexponential decay function, and it is found that the average lifetime decreases with increasing the concentration of Zn in Cd_xZn_1-xS alloy nanocrystals. A stochastic model of carrier relaxation dynamics of Cd_xZn_1-xS alloy nanocrystals has been proposed to estimate the values of the radiative relaxation rate, nonradiative relaxation rate, and number of trap states. Results show that the radiative and nonradiative relaxation rates and the number of trap states increase with increasing the lattice strain of the alloy nanocrystals. Such alloy nanocrystals should have great potentials for nonlinear optical properties, photovoltaic devices, and solar cell.