Study On Electron Scattering Rate Of InGaAsP / InP Ladder Quantum Well

With the development of the preparation technology for low dimension semiconductor materials, various shapes of low-dimensional semiconductor structures have been fabricated out. As a kind of important low-dimensional semiconductor structures, stepped quantum well(SQW) has many physical properties and is widely used in semiconductor optical amplifier which is the representative of optical communication devices. InGaAsP material has important application in the field of optical communication due to its excellent physical properties. The carrier scattering is an inherent attribute of the semiconductor material, it can influence the working performance of semiconductor devices, therefore the researches on the carrier scattering rate have positive significance for the improvement in the performance of optical communication devices and communication quality.Within the framework of the effective-mass envelope-function approximation theory, the electron scattering rate and mean scattering rate in In1-xGaxAsyP1-y/InP SQW is studied adopting the shooting method and Fermi’s golden rule. The main contents are presented as follows:1. The related concepts and properties of quantum well(QW) and SQW are introduced briefly. The physical properties and applications of InGaAsP material and the principle of carrier scattering are summed up.2. The scattering rate via longitudinal optical(LO) phonon emission for an electron and the mean scattering rate via LO phonons emission for electrons initially in the first excited subband and finally in the ground subband in In1-xGaxAsyP1-y/InP SQW is studied. The results show that the scattering rate decreases with increasing initial electron energy when the separation between initial electron energy and the ground state energy is greater than the LO phonon energy. The interrupt of the scattering rate happens when the separation between initial electron energy and the ground state energy is less than the LO phonon energy. The scattering rate reaches the maximum value when the separation between initial electron energy and the ground state energy is equal to the LO phonon energy. When the subband separation is greater than the LO phonon energy, the mean scattering rate increases with increasing Ga composition and well width, decreases with increasing As composition and stepped layer height. However, when the subband separation is less than the LO phonon energy, its change tendency is contrary. The mean scattering rate reaches the maximum value when the subband separation is equal to the LO phonon energy. When the electron temperature is relatively low, the electron temperature does not have great influence on the mean scattering rate. When the electron temperature is relatively high, the scattering rate and the mean scattering rate increases with rising electron temperature.3. The scattering rate and the mean scattering rate for two electrons and multiple electrons initially in the first excited subband and finally in the ground subband in In1-xGaxAsyP1-y/InP SQW is studied. The results show that the electron-electron scattering rate decreases with increasing initial electron energy. The mean scattering rate increases with increasing Ga composition, well width and carrier density, decreases with increasing As composition, stepped layer height and subband separation. When the stepped layer height is low, the stepped layer height has obvious influence on the mean scattering rate. When the electron temperature is relatively low, the scattering rate and the mean scattering rate decrease with decreasing electron temperature. When the electron temperature is relatively high, the electron temperature does not have obvious influence on the scattering rate and the mean scattering rate, the scattering rate and the mean scattering rate decrease slowly as the electron temperature rises.4. On the basis of the effective-mass envelope-function approximation theory, shooting method and Fermi’s golden rule, the influence of the applied electric field and magnetic field on the scattering rate and mean scattering rate for electron-LO phonon and electron-electron initially in the first excited subband and finally in the ground subband in In1-xGaxAsyP1-y/InP SQW are studied combining the theoretical expression for the Hamiltonian of electron under the applied electric field and magnetic field. The results show that both the scattering rate and the mean scattering rate for electron-LO phonon and electron-electron decrease with increasing applied electric field and magnetic field unde the conditions of the same initial electron energy and electron temperature, the fixed well width and stepped layer widths. When the applied electric field and magnetic field is relatively strong, the influence of the applied electric field and magnetic field on the scattering rate and mean scattering rate is relatively obvious.