The electronic properties of CdTe/ZnTe quantum rings （QRs） are investigated as functions of size and temperature using an eight-band strain-dependent k.p Hamiltonian. The size effects of diameter and height on the s...The electronic properties of CdTe/ZnTe quantum rings （QRs） are investigated as functions of size and temperature using an eight-band strain-dependent k.p Hamiltonian. The size effects of diameter and height on the strain distributions around the QRs are studied. We find that the interband transition energy, defined as the energy difference between the ground electronic and the ground heavy-hole subbands, increases with the increasing QR inner diameter regardless of the temperature, while the interband energy decreases with the increasing QR height, This is attributed to the reduction of subband energies in both the conduction and the valence bands due to the strain effects. Our model, in the framework of the finite element method and the theory of elasticity of solids, shows a good agreement with the temperature-dependent photoluminescence measurement of the interband transition energies.展开更多
Optical properties of graded InGaN/GaN quantum well(QW)lasers are analyzed as improved gain media for laser diodes emitting near 500 nm.These results are compared with those of conventional InGaN/GaN QW structures.The...Optical properties of graded InGaN/GaN quantum well(QW)lasers are analyzed as improved gain media for laser diodes emitting near 500 nm.These results are compared with those of conventional InGaN/GaN QW structures.The heavy-hole effective mass around the topmost valence band is found to nearly not be affected by the inclusion of the graded layer.The graded InGaN/GaN QW structure shows a much larger matrix element than the conventional InGaN/GaN QW structure.The radiative current density dependences of the optical gain are similar to each other.However,the graded QW structure is expected to have lower threshold current density than the conventional QW structure because the former has a lower threshold carrier density than the latter.展开更多
基金Project supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)the Ministry of Education,Science,and Technology,Korea (Grant No.2010-0024703)
文摘The electronic properties of CdTe/ZnTe quantum rings （QRs） are investigated as functions of size and temperature using an eight-band strain-dependent k.p Hamiltonian. The size effects of diameter and height on the strain distributions around the QRs are studied. We find that the interband transition energy, defined as the energy difference between the ground electronic and the ground heavy-hole subbands, increases with the increasing QR inner diameter regardless of the temperature, while the interband energy decreases with the increasing QR height, This is attributed to the reduction of subband energies in both the conduction and the valence bands due to the strain effects. Our model, in the framework of the finite element method and the theory of elasticity of solids, shows a good agreement with the temperature-dependent photoluminescence measurement of the interband transition energies.
基金by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science and Technology(2009-0071446).
文摘Optical properties of graded InGaN/GaN quantum well(QW)lasers are analyzed as improved gain media for laser diodes emitting near 500 nm.These results are compared with those of conventional InGaN/GaN QW structures.The heavy-hole effective mass around the topmost valence band is found to nearly not be affected by the inclusion of the graded layer.The graded InGaN/GaN QW structure shows a much larger matrix element than the conventional InGaN/GaN QW structure.The radiative current density dependences of the optical gain are similar to each other.However,the graded QW structure is expected to have lower threshold current density than the conventional QW structure because the former has a lower threshold carrier density than the latter.
