Theoretical investigation of electron-phonon interaction in one-dimensional Si quantum dot array interconnected with silicon oxide layers

Abstract

Electronic and phononic states and their interactions in one-dimensional arrays of Si quantum dots interconnected with thin oxide layers is theoretically investigated. Electronic states under low electric field condition are obtained in the Kronig-Penny potential. Approximate expression for phonon wave functions is developed and numerically calculated using the linear atomic chain model. Simulated dispersion relation shows acoustic phonon modes, phonon band gaps, and confined optical phonon modes. Electron-phonon scattering rate is written using a one-dimensional expression. Intraminiband scattering rates and energy relaxation rates are simulated both for absorption and emission processes. The scattering rate varies from ~10¹² to ~ 10¹⁴, depending on the initial electron energy. The scattering rate for absorption/emission processes rapidly decreases at near the top/bottom of minibands due to limited number of phonon branches that can mediate the scattering processes. Negative energy relaxation rate is observed near the bottom of minibands, which is due to larger scattering rate for absorption process and smaller phonon energy mediating the scatterings for emission process. The scattering rate for absorption decreases rapidly with decreasing temperature. Once the temperature drops down to 100K, the energy relaxation rate for emission process dominates the absorption process.

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