Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,quasi-confined （QC） optical phonon modes and electron-QC phonon coupling functions in quasi-one-dimensional （QID） wurtzite quantum well ...Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,quasi-confined （QC） optical phonon modes and electron-QC phonon coupling functions in quasi-one-dimensional （QID） wurtzite quantum well wires （QWWs） are deduced and analyzed. Numerical calculations on an AIN/GaN/AIN wurtzite QWW are performed. The results reveal that the dispersions of the QC modes are quite obvious only when the free wavenumber kz in the z-direction and the azimuthal quantum number m are small. The reduced behavior of the QC modes in wurtzite quantum systems is clearly observed. Through the discussion of the electron-QC mode coupling functions,it is found that the lower-frequency QC modes in the high-frequency region play a more important role in the electron-QC phonon interactions. Moreover,our computations also prove that kz and m have a similar influence on the electron-QC phonon coupling properties.展开更多
We investigated the properties of polarons in a wurtzite ZnO/MgxZn1-xO quantum well by adopting a modified Lee–Low–Pines variational method, giving the ground state energy, transition energy, and phonon contribution...We investigated the properties of polarons in a wurtzite ZnO/MgxZn1-xO quantum well by adopting a modified Lee–Low–Pines variational method, giving the ground state energy, transition energy, and phonon contributions from various optical-phonon modes to the ground state energy as functions of the well width and Mg composition. In our calculations, we considered the effects of confined optical phonon modes, interface-optical phonon modes, and half-space phonon modes, as well as the anisotropy of the electron effective band mass, phonon frequency, and dielectric constant. Our numerical results indicate that the electron–optical phonon interactions importantly affect the polaronic energies in the ZnO/MgxZn1-xO quantum well. The electron–optical phonon interactions decrease the polaron energies. For quantum wells with narrower wells, the interface optical phonon and half-space phonon modes contribute more to the polaronic energies than the confined phonon modes. However, for wider quantum wells, the total contribution to the polaronic energy mainly comes from the confined modes. The contributions of the various phonon modes to the transition energy change differently with increasing well width. The contribution of the half-space phonons decreases slowly as the QW width increases, whereas the contributions of the confined and interface phonons reach a maximum at d ≈ 5.0 nm and then decrease slowly. However,the total contribution of phonon modes to the transition energy is negative and increases gradually with the QW width of d.As the composition x increases, the total contribution of phonons to the ground state energies increases slowly, but the total contributions of phonons to the transition energies decrease gradually. We analyze the physical reasons for these behaviors in detail.展开更多
The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field...The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field and different phonon modes including interface, confined and half-space phonon modes are considered in our calculation. The results for a zinc-blende quantum well are also given for comparison. It is found that the main contribution to the transition energy comes from half-space and interface phonon modes when the well width is very small while the confined modes play a more important role in a wider well due to the location of the electron wave function. As the well width increases, the cyclotron mass of magnetopolarons first increases to a maximum and then decreases either with or without the built-in electric field in the wurtzite structure and the built-in electric field slightly reduces the cyclotron mass. The variation of cyclotron mass in a zinc-blende structure is similar to that in a wurtzite structure. With the increase of external magnetic field, the cyclotron mass of polarons almost linearly increases. The cyclotron frequency of magnetopolarons is also discussed.展开更多
Based on the dielectric continuum model and Loudon＇s uniaxial crystal model, the properties of the quasi. confined （QC） optical phonon dispersions and the electron-QC phonons coupling functions in an asymmetric wur...Based on the dielectric continuum model and Loudon＇s uniaxial crystal model, the properties of the quasi. confined （QC） optical phonon dispersions and the electron-QC phonons coupling functions in an asymmetric wurtzite quantum well （QW） are deduced via the method of electrostatic .potential expanding. The present theoretical scheme can naturally reduce to the results in symmetric wurtzite QW once a set of symmetric structural parameters are chosen. Numerical calculations on an asymmetric AlN/GaN/AIo,15 Gao.85N Wurtzite Q W are performed. A detailed comparison with the symmetric wurtzite QW was also performed. The results show that the structural asymmetry of wurtzite QW changes greatly the dispersion frequencies and the electrostatic potential distributions of the QC optical phonon modes.展开更多
A detailed numerical calculation on the phonon-assisted intersubband transition rates of electrons in wurtzite CaN/InxGal-xN quantum wells is presented. The quantum-confined Stark effect, induced by the built-in elect...A detailed numerical calculation on the phonon-assisted intersubband transition rates of electrons in wurtzite CaN/InxGal-xN quantum wells is presented. The quantum-confined Stark effect, induced by the built-in electric field, and the ternary mixed crystal effect are considered. The electron states are obtained by iteratively solving the coupled SchrSdinger and Poisson equations. The dispersion properties of each type of phonon modes are considered in the derivation of Fermi＇s golden rule to evaluate the transition rates. It is indicated that the interface and half- space phonon scattering play an important role in the process of 1 2 radiative transition. The transition rate is also greatly reduced by the built-in electric field. This work can be helpful for the structural design and simulation of new semiconductor lasers.展开更多
The polar interface optical （IO） and surface optical （SO） phonon modes and the corresponding Froehlich electron phonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire （QWR...The polar interface optical （IO） and surface optical （SO） phonon modes and the corresponding Froehlich electron phonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire （QWR） are derived and studied by employing the transfer matrix method in the dielectric continuum approximation and Loudon＇s uniaxial crystal model. A numerical calculation of a freestanding wurtzite GaN/AlN QWR is performed. The results reveal that for a relatively large azimuthal quantum number m or wave-number kz in the free z-direction, there exist two branches of IO phonon modes localized at the interface, and only one branch of SO mode localized at the surface in the system. The degenerating behaviours of the IO and SO phonon modes in the wurtzite QWR have also been clearly observed for a small kz or m. The limiting frequency properties of the IO and SO modes for large kz and m have been explained reasonably from the mathematical and physical viewpoints. The calculations of electron-phonon coupling functions show that the high-frequency IO phonon branch and SO mode play a more important role in the electron phonon interaction.展开更多
The interface-optical-propagating （IO-PR） mixing phonon modes of a quasi-zero-dimensional （QOD） wurtzite cylindrical quantum dot （QD） structure are derived and studied by employing the macroscopic dielectric con...The interface-optical-propagating （IO-PR） mixing phonon modes of a quasi-zero-dimensional （QOD） wurtzite cylindrical quantum dot （QD） structure are derived and studied by employing the macroscopic dielectric continuum model. The analytical phonon states of IO-PR mixing modes are given. It is found that there are two types of IO-PR mixing phonon modes, i.e. p-IO//z-PR mixing modes and the z-IO//p-PR mixing modes existing in QOD wurtzite QDs. And each IO-PR mixing modes also have symmetrical and antisymmetrieal forms. Via a standard procedure of field quantization, the Frohlich Hamiltonians of electron-（IO-PR） mixing phonons interaction are obtained. Numerical calculations on a wurtzite GaN cylindrical QD are performed. The results reveal that both the radial-direction size and the axial-direction size as well as the dielectric matrix have great influence on the dispersive frequencies of the IO-PR mixing phonon modes. The limiting features of dispersive curves of these phonon modes are discussed in depth. The phonon modes ＂reducing＂ behavior of wurtzite quantum confined systems has been observed obviously in the structures. Moreover, the degenerating behaviors of the IO-PR mixing phonon modes in wurtzite QOD QDs to the IO modes and PR modes in wurtzite Q2D QW and QID QWR systems are analyzed deeply from both of the viewpoints of physics and mathematics.展开更多
The properties of polar optical phonon vibrations in a quasi-zero- dimensional （QOD） anisotropic wurtzite cylindrical quantum dot （QD） are analyzed based on the dielectric continuum model and Loudon＇s uniaxial cr...The properties of polar optical phonon vibrations in a quasi-zero- dimensional （QOD） anisotropic wurtzite cylindrical quantum dot （QD） are analyzed based on the dielectric continuum model and Loudon＇s uniaxial crystal model. The analytical electrostatic potentials of the phonon vibrations in the systems are deduced and solved exactly. The result shows that there exist four types of polar mixing optical phonon modes in the QOD wurtzite cylindrical QD systems. The dispersive equations and electron-phonon coupling function for the quasi-confined-half-space （QC-HS） mixing modes are derived and discussed. It is found that once the radius or the height of the QD approach infinity, the dispersive equations of the QC-HS mixing modes in the QOD cylindrical QD can naturally reduce to those of the QC and HS modes in Q2D QWs or Q1D QWWs systems. This has been analyzed reasonably from both of physicM and mathematical viewpoints.展开更多
为了研制满足光纤通讯需求的高性能半导体激光器,对压应变In Ga As Sb/Ga As Sb量子阱激光器有源区进行了研究。根据应变量子阱能带理论、固体模型理论和克龙尼克-潘纳模型,确定了激射波长与量子阱材料组分及阱宽的关系。基于Lastip软...为了研制满足光纤通讯需求的高性能半导体激光器,对压应变In Ga As Sb/Ga As Sb量子阱激光器有源区进行了研究。根据应变量子阱能带理论、固体模型理论和克龙尼克-潘纳模型,确定了激射波长与量子阱材料组分及阱宽的关系。基于Lastip软件建立了条宽为50μm、腔长为800μm的半导体激光器仿真模型,模拟器件的输出特性,讨论了量子阱个数对器件光电特性的影响。结果表明:当量子阱组分为In0.44Ga0.56As0.92Sb0.08/Ga As0.92Sb0.08、阱宽为9 nm、量子阱个数为2时,器件的性能达到最佳,阈值电流为48 m A,斜率效率为0.76 W/A。展开更多
文摘Based on the dielectric continuum model and Loudon＇s uniaxial crystal model,quasi-confined （QC） optical phonon modes and electron-QC phonon coupling functions in quasi-one-dimensional （QID） wurtzite quantum well wires （QWWs） are deduced and analyzed. Numerical calculations on an AIN/GaN/AIN wurtzite QWW are performed. The results reveal that the dispersions of the QC modes are quite obvious only when the free wavenumber kz in the z-direction and the azimuthal quantum number m are small. The reduced behavior of the QC modes in wurtzite quantum systems is clearly observed. Through the discussion of the electron-QC mode coupling functions,it is found that the lower-frequency QC modes in the high-frequency region play a more important role in the electron-QC phonon interactions. Moreover,our computations also prove that kz and m have a similar influence on the electron-QC phonon coupling properties.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11264027 and 11364030)the Project of Prairie Excellent Specialist of Inner Mongolia,Chinathe "Thousand,Hundred and Ten" Talent Training Project Foundation of Inner Mongolia Normal University,China(Grant No.RCPY-2-2012-K-039)
文摘We investigated the properties of polarons in a wurtzite ZnO/MgxZn1-xO quantum well by adopting a modified Lee–Low–Pines variational method, giving the ground state energy, transition energy, and phonon contributions from various optical-phonon modes to the ground state energy as functions of the well width and Mg composition. In our calculations, we considered the effects of confined optical phonon modes, interface-optical phonon modes, and half-space phonon modes, as well as the anisotropy of the electron effective band mass, phonon frequency, and dielectric constant. Our numerical results indicate that the electron–optical phonon interactions importantly affect the polaronic energies in the ZnO/MgxZn1-xO quantum well. The electron–optical phonon interactions decrease the polaron energies. For quantum wells with narrower wells, the interface optical phonon and half-space phonon modes contribute more to the polaronic energies than the confined phonon modes. However, for wider quantum wells, the total contribution to the polaronic energy mainly comes from the confined modes. The contributions of the various phonon modes to the transition energy change differently with increasing well width. The contribution of the half-space phonons decreases slowly as the QW width increases, whereas the contributions of the confined and interface phonons reach a maximum at d ≈ 5.0 nm and then decrease slowly. However,the total contribution of phonon modes to the transition energy is negative and increases gradually with the QW width of d.As the composition x increases, the total contribution of phonons to the ground state energies increases slowly, but the total contributions of phonons to the transition energies decrease gradually. We analyze the physical reasons for these behaviors in detail.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10964007)the Natural Science Foundation of Inner Mongolia,China (Grant No. 2009MS0110)
文摘The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field and different phonon modes including interface, confined and half-space phonon modes are considered in our calculation. The results for a zinc-blende quantum well are also given for comparison. It is found that the main contribution to the transition energy comes from half-space and interface phonon modes when the well width is very small while the confined modes play a more important role in a wider well due to the location of the electron wave function. As the well width increases, the cyclotron mass of magnetopolarons first increases to a maximum and then decreases either with or without the built-in electric field in the wurtzite structure and the built-in electric field slightly reduces the cyclotron mass. The variation of cyclotron mass in a zinc-blende structure is similar to that in a wurtzite structure. With the increase of external magnetic field, the cyclotron mass of polarons almost linearly increases. The cyclotron frequency of magnetopolarons is also discussed.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 60276004 and 6939007,3, the Scientilic Research Foundation for the Returned 0overseas Chinese Scholars State Education Ministry of China
文摘Based on the dielectric continuum model and Loudon＇s uniaxial crystal model, the properties of the quasi. confined （QC） optical phonon dispersions and the electron-QC phonons coupling functions in an asymmetric wurtzite quantum well （QW） are deduced via the method of electrostatic .potential expanding. The present theoretical scheme can naturally reduce to the results in symmetric wurtzite QW once a set of symmetric structural parameters are chosen. Numerical calculations on an asymmetric AlN/GaN/AIo,15 Gao.85N Wurtzite Q W are performed. A detailed comparison with the symmetric wurtzite QW was also performed. The results show that the structural asymmetry of wurtzite QW changes greatly the dispersion frequencies and the electrostatic potential distributions of the QC optical phonon modes.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60966001)the Science Foundation of Inner Mongolia Autonomous Region, China (Grant No. 2010BS0102)
文摘A detailed numerical calculation on the phonon-assisted intersubband transition rates of electrons in wurtzite CaN/InxGal-xN quantum wells is presented. The quantum-confined Stark effect, induced by the built-in electric field, and the ternary mixed crystal effect are considered. The electron states are obtained by iteratively solving the coupled SchrSdinger and Poisson equations. The dispersion properties of each type of phonon modes are considered in the derivation of Fermi＇s golden rule to evaluate the transition rates. It is indicated that the interface and half- space phonon scattering play an important role in the process of 1 2 radiative transition. The transition rate is also greatly reduced by the built-in electric field. This work can be helpful for the structural design and simulation of new semiconductor lasers.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 60276004 and 60390073） and the Natural Science Foundation of Guangzhou Education Bureau, China （Grant No 2060）. Acknowledgement The author would like to thank Professor J J Shi for detailed and valuable discussion.
文摘The polar interface optical （IO） and surface optical （SO） phonon modes and the corresponding Froehlich electron phonon-interaction Hamiltonian in a freestanding multi-layer wurtzite cylindrical quantum wire （QWR） are derived and studied by employing the transfer matrix method in the dielectric continuum approximation and Loudon＇s uniaxial crystal model. A numerical calculation of a freestanding wurtzite GaN/AlN QWR is performed. The results reveal that for a relatively large azimuthal quantum number m or wave-number kz in the free z-direction, there exist two branches of IO phonon modes localized at the interface, and only one branch of SO mode localized at the surface in the system. The degenerating behaviours of the IO and SO phonon modes in the wurtzite QWR have also been clearly observed for a small kz or m. The limiting frequency properties of the IO and SO modes for large kz and m have been explained reasonably from the mathematical and physical viewpoints. The calculations of electron-phonon coupling functions show that the high-frequency IO phonon branch and SO mode play a more important role in the electron phonon interaction.
基金Supported by National Natural Science Foundation of China under Grant Nos. 60711120203, 60890193STPAA of Guangzhou City under Grant No. 2060
文摘The interface-optical-propagating （IO-PR） mixing phonon modes of a quasi-zero-dimensional （QOD） wurtzite cylindrical quantum dot （QD） structure are derived and studied by employing the macroscopic dielectric continuum model. The analytical phonon states of IO-PR mixing modes are given. It is found that there are two types of IO-PR mixing phonon modes, i.e. p-IO//z-PR mixing modes and the z-IO//p-PR mixing modes existing in QOD wurtzite QDs. And each IO-PR mixing modes also have symmetrical and antisymmetrieal forms. Via a standard procedure of field quantization, the Frohlich Hamiltonians of electron-（IO-PR） mixing phonons interaction are obtained. Numerical calculations on a wurtzite GaN cylindrical QD are performed. The results reveal that both the radial-direction size and the axial-direction size as well as the dielectric matrix have great influence on the dispersive frequencies of the IO-PR mixing phonon modes. The limiting features of dispersive curves of these phonon modes are discussed in depth. The phonon modes ＂reducing＂ behavior of wurtzite quantum confined systems has been observed obviously in the structures. Moreover, the degenerating behaviors of the IO-PR mixing phonon modes in wurtzite QOD QDs to the IO modes and PR modes in wurtzite Q2D QW and QID QWR systems are analyzed deeply from both of the viewpoints of physics and mathematics.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 60276004 and 60390073 and the Natural Science Foundation of Guangzhou Education Bureau under Grant No. 2060
文摘The properties of polar optical phonon vibrations in a quasi-zero- dimensional （QOD） anisotropic wurtzite cylindrical quantum dot （QD） are analyzed based on the dielectric continuum model and Loudon＇s uniaxial crystal model. The analytical electrostatic potentials of the phonon vibrations in the systems are deduced and solved exactly. The result shows that there exist four types of polar mixing optical phonon modes in the QOD wurtzite cylindrical QD systems. The dispersive equations and electron-phonon coupling function for the quasi-confined-half-space （QC-HS） mixing modes are derived and discussed. It is found that once the radius or the height of the QD approach infinity, the dispersive equations of the QC-HS mixing modes in the QOD cylindrical QD can naturally reduce to those of the QC and HS modes in Q2D QWs or Q1D QWWs systems. This has been analyzed reasonably from both of physicM and mathematical viewpoints.
文摘为了研制满足光纤通讯需求的高性能半导体激光器,对压应变In Ga As Sb/Ga As Sb量子阱激光器有源区进行了研究。根据应变量子阱能带理论、固体模型理论和克龙尼克-潘纳模型,确定了激射波长与量子阱材料组分及阱宽的关系。基于Lastip软件建立了条宽为50μm、腔长为800μm的半导体激光器仿真模型,模拟器件的输出特性,讨论了量子阱个数对器件光电特性的影响。结果表明:当量子阱组分为In0.44Ga0.56As0.92Sb0.08/Ga As0.92Sb0.08、阱宽为9 nm、量子阱个数为2时,器件的性能达到最佳,阈值电流为48 m A,斜率效率为0.76 W/A。
