Theoretical Studies On Raman Scattering In Double Quantum Wells

The low-dimensional semiconductor structures are new development for thesemiconductor industry in recent years, and they e?ectively promote the researchand application of semiconductor in a new level. The concept of superlattices andthe accomplishment of semiconductor superlattices, quantum-well, quantum-wireand quantum-dot low-dimensional materials thoroughly change the design ideas ofphotoelectric devices, which make the design and manufacture of semiconductor devicesfrom"impurities project"to"energy band engineering". New fields, such as"the tailorability of electrical and optical properties"appeared, which make peoplecross into a new generation of semiconductor devices based on the characteristics ofquantum e?ects and low-dimensional structures. Therefore, it has been a hot topicfor people to know the physical properties of these structures. Raman scattering, forits convenience and no damage to the materials being measured, has become one ofthe most e?ective methods to provide direct information in the energy band structureand di?erent physical properties of the low-dimensional semiconductor systems. Inthe present dissertation, the electron Raman scattering in double quantum wells arestudied theoretically and the Raman di?erential cross sections are investigated. Thein?uence of the asymmetry of double quantum wells and the external electric field onthe Raman scattering spectrum are also analyzed. The dissertation includes four chapters.In the first chapter, the general characters and applications of low-dimensionalsemiconductor structures are summarized brie?y and a simple introduction to the currentresearch of Raman scattering in low-dimensional structures is given.In the second chapter, electron Raman scattering is investigated in double triangularand double rectangle quantum wells. With the e?ective mass approximation theory,the expression of di?erential cross section is deduced, and the selection rules forthe processes are also studied. Numerical results and discussions are presented forasymmetry of double quantum wells and di?erent Al doping component. Singularitiesin the spectrum are found and interpreted. Results show that the scattering spectrumdepend not only on the asymmetry of double quantum wells, but also on the Aldoping component. The spectrum yield a red shift with increasing the asymmetry ofdouble quantum wells or decreasing the doping component. And the same phenomenon of red shift caused by the asymmetry is also observed in double rectangular quantum wells.In the third chapter, a theoretical study of electron Raman scattering process indouble triangular quantum wells with the external electric field is investigated. Theexpression of differential cross section is deduced and the selection rules are also given.The relationship between differential cross section and the intensity of electric fieldis revealed, and the effects of applied electric field on quantum-well structures arealso analyzed. Results show that the increasing electric field is equivalent to enhancethe asymmetry of quantum wells. And when the size of the potential well is set, thescattering spectrum appear a red shift with the increasement of electric field.In the last chapter, a brief summary of this paper, including the theories and theresults is given, and the shortage and further research are also mentioned.