Study On The Scattering Of Electron - IP Phonon In Cd _1-x Mn Te / CdTe Quantum Wells

Ⅱ-Ⅵ compound semiconductor CdTe has wide bandgap and physical properties satisfied direct transition, and the wide band direct transition semiconductor is the ideal material for developing optoelectronic technology, which is widely used in solid state luminescence, laser, infrared detector, the production of high-speed optical switch and other precision optical devices. If Mn2+ is mixed in CdTe, the special physical properties of CdMnTe material can be possessed such as magnetic and semiconducting. For example, the optical isolation devices can be fabricated using its Faraday effect, which can improve the efficiency of light in the transmission process. The theoretical study on the optical properties of Cd_1-xMn_xTe/CdTe quantum well can not only enrich our knowledge of low dimensional semiconductor optical properties, but also design and fabricate various high performance optical communication devices. Therefore, it has a very important significance.Based on the effective mass envelope function approximation theory and the shooting method, the electron-LO phonon scattering rate of the first excited state to the ground state in three kinds of different quantum wells is calculated theoretically using Fermi’s golden rule. And the main contents are as follows:1. In the first part, the development of optical communication, the application of quantum well in optical communication and Cd_1-xMn_xTe/CdTe material is introduced briefly. The electron-LO phonon scattering rate is also described.2. The research methods for calculating the electron-Lo phonon scattering rate are presented in this thesis, which mainly include effective mass envelope function approximation theory, shooting method and Fermi’s golden rule.3. The electron-LO phonon scattering rate of the first excited state to the ground state in Cd_1-xMn_xTe/CdTe single quantum well is calculated theoretically using Fermi’s golden rule. And the mean scattering rate changing with the well width, temperature and Mn concentration is also discussed. The result shows that the electron-LO phonon scattering rate decreases with the increase of the total initial energy gradually. The mean scattering rate increases up to their maximum, then begin to decrease as the well width increase. In the case of low temperature, the variation of mean scattering rate is not obvious. However when the temperature is relatively high, the mean scattering rate increases distinctly. Finally, the effect of the external electric field on the scattering rate and mean scattering rate is studied. The result shows that the external electric field will reduce the scattering rate and mean scattering rate.4. The electron-LO phonon scattering rate in Cd_1-xMn_xTe/CdTe double quantum wells is studied. The theoretical calculation shows that: the mean scattering rate has its maximum with the increase of the well width. It appears at the point where the energy is equal to the phonon energy. The electron-LO phonon mean scattering rate increases monotonically with the increase of temperature. With the increasing of the electric field, the electron-LO phonon scattering rate and the mean scattering rate decreased gradually. Due to the coupling effect in the double quantum well, the mean scattering rate can be reduced. The calculation results are of great significance to the design of Cd_1-xMn_xTe/CdTe optoelectronic devices.5. The scattering rate of electron-LO phonon in Cd_1-xMn_xTe/CdTe parabolic quantum well is discussed. The electron-LO phonon scattering rate transited from the first excited state to the ground state of the Cd_1-xMn_xTe/CdTe parabolic quantum well is calculated, and the mean scattering rate changing with the well width, temperature and Mn concentration is discussed. Finally, the scattering rates of single quantum well, double quantum well and parabolic quantum well are compared.The mean scattering rate of double quantum well is lower than single quantum well, which is related to the coupling effect of the double quantum well. The quantum confinement potential of the parabolic quantum well is gradient, and its scattering rate is lower than single quantum well.