Charge Carrier-Plasmon Interactions at the (In, Pb, La)/CusSe Interfaces رسالة ماجستير

Abstract

In this thesis, we have studied the structural and optical performances of CuSe thin films which are grown onto thin transparent Indium, Lanthanum and Lead metal substrates. The metal/CuSe films which are prepared by thermal evaporation technique under vacuum pressure of 10 mbar displayed different characteristics based on the metal type. Particularly, while the (In, Pb)/CuSe displayed the same value of cubic lattice constant, the La/CuSe exhibited shorter lattice constants. The structural parameters, accordingly are also influenced by the substrate type. Namely, the defect density, the staking faults and the stress, exhibit higher values in the presence of La compared to of (In, Pb)/CuSe interfaces. The grain size decreases from 28 nm for glass/CuSe to l16 nm for La/CuSe while it increases to 36nm, 33nm

in the presence of In and Pb substrates.

On the other hand, the optical spectroscopy studies which are carried out in the incident light wavelength range of 300-1100 nm revealed a smaller effect of the presence of metals on the value of the energy band gap and remarkable effect dielectric constant in the high frequency range. lIn addition, the Drude-Lorentz analysis and modeling on the imaginary part of the dielectric constant have shown that the scattering time at femtosecond level is increased in the presence of metal substrates from 1.50 to 2.50, 1.55 1.80 in the presence of glass, In, La and Pb substrates, respectively. Such behavior indicates that the electronic friction in CuSe

has decreased and the electronic transport become more effective. Consistently, the drift mobility is increased in the presence of metals. With the value of plasmon frequency are 3.38, 2.71, 1.66 and 2.38 being in the gigahertz range for glass, In, La and Pb substrates, respectively. The In, La, Pb/CuSe can be accepted as promising

interfaces for use as plasmonic devices and as microwave filters.