Polaron Energy And Correlation Parameters In Ternary Mixed Crystal A_xB_1-xC

Ternary mixed crystals AxB1-xC are extensively researched and used in artificial layered structures and low dimensionality systems, e.g. superlattices, heterostructures, quantum wells, quantum dots and quantum wires etc, due to their unique crystal texture and physical properties quite different from binary crystals, such as the static and optical dielectric constants, coupling constant, optical phonon frequency and band-gap energy can be controlled directly by the component concentrations. Therefore, they are considered to be very important materials form any new multi-functional electronic and photo-electronic high precision devices. In recent years, the studies of elementary excitation in ternary mixed crystals, such as excitons, phonons, exciton binding energy and the exciton-LO-phonon interaction energy, have received persistent and extensive attention and become one of the important research fields in condensed matter. In this thesis, we investigated the energy of polaron and related parameters problems in ternary mixed crystals AxB1-xC materials.The fundamental properties of ternary mixed crystals AxB1-xC quantum wells are investigated theoretically. The mode number and the energies of optical phonons, the coupling constant, high frequency and static dielectric constants of crystals, are obtained by using an improved mixed crystal theory. The carrier-longitudinal optical phonon interaction in ternary mixed crystals is studied by a perturbational polaron theory. Based on the present theoretical results, the numerical results of the parameters as functions of the composition content in ternary mixed crystals InxGa1-xN, SexS1-xZn, GaxAl1-xAs, SbxAs1-xGa, AlxGa1-xN and RbxK1-xCl are obtained, and the results are investigated by using the linear interpolation method. Theoretical result supports that the linear interpolation method used to estimate the Frohlich constants and the polaronic correction of the electron effective masses is valid in the weak electron-phonon coupling case. The results also show that the polaron energy and correlation parameters with the composition x, and it is more visible in ternary mixed crystal AxB1-xC. Such as the ε∞and ε0of electron-phonon interaction in InxGa1-xN, Se xS1-xZn, GaxAl1-xAs, SbxAs1-xGa and RbxK1-xCl increases with increasing the composition x, but the case is contrary in AlxGa1-xN mixed crystals.