The electronic structures of the zinc-blende GaN/Ga0.85Al0.15N compressively strained superlattices and quantum wells are investigated using a 6 × 6 Hamiltonian model (including the heavy hole, light hole and spin-orbit splitting band). The energy bands, wavefunctions and optical transition matrix elements are calculated. It is found that the light hole couples with the spin-orbit splitting state even at the k = 0 point, resulting in the hybrid states. The heavy hole remains a pure heavy hole state at k = 0. The optical transitions from the hybrid valence states to the conduction states are determined by the transitions of the light hole and spin-orbit splitting states to the conduction states. The transitions from the heavy hole, light hole and spin-orbit splitting states to the conduction states obey the selection rule Δn = 0. The band structures obtained in this work will be valuable in designing GaN/GaAlN based optoelectronic devices. © 1996 Academic Press Limited.

Fan W. J.;Li M. F.;Chong T. C.;Xia J. B.

Superlattices and Microstructures

1996

GaAs/GaAlAs quantum well mid-infrared (3-5μm) detectors and GaAs/GaAlAs quantum well two-color (3-5μm and 8-12μm) infrared detectors were fabricated. GaAs/GaAlAs quantum well mid-infrared (3-5μm) detectors are photovoltaic, and their black-body detectivity (D bb ) at 85K is 3.0×10 ⁹ cm·Hz ^1/2 /W. GaAs/GaAlAs quantum well two-color (3-5μm and 8-12μm) infrared detectors are two terminal biascontrolled devices, and their photoresponse at zero bias is only within 3-5μm while the photoresponse at a bias of 2.0 V is only within 8-12μm.

Zhang Yaohui;Jiang Desheng;Xia Jianbai;Liu Wei;Cui Liqiu;Yang Xiaoping;Song Chunying;Zheng Houzhi

Pan Tao Ti Hsueh Pao Chinese Journal of Semiconductors

1996

The electronic properties of wide energy gap zinc-blende structure GaN, AlN and their alloys Ga1-xAlxN are investigated using the empirical pseudopotential method. Electron and hole Effective mass parameters, hydrostatic and shear deformation potential constants of the valence band at Γ and those of the conduction band at Γ and X are obtained. The energies of Γ, X, L conduction valleys of Ga1-xAlxN alloy versus Al fraction x are also calculated. The information will be useful for the design of lattice mismatched heterostructure optoelectronic devices in the blue light range.

Fan W. J.;Li M. F.;Chong T. C.;Xia J. B.

Solid State Communications

1996

A transfer matrix approach is presented for the study of electron conduction in an arbitrarily shaped cavity structure embedded in a quantum wire. Using the boundary conditions for wave functions, the transfer matrix at an interface with a discontinuous potential boundary is obtained for the first time. The total transfer matrix is calculated by multiplication of the transfer matrix for each segment of the structure as well as numerical integration of coupled second-order differential equations. The proposed method is applied to the evaluation of the conductance and the electron probability density in several typical cavity structures. The effect of the geometrical features on the electron transmission is discussed in detail. In the numerical calculations, the method is found to be more efficient than most of the other methods in the literature and the results are found to be in excellent agreement with those obtained by the recursive Green's function method.

Sheng Wei-Dong;Xia Jian-Bai

Journal of Physics Condensed Matter

1996

Based on the valence subbands of the zinc-blende GaN/Ga0.85Al0.15N strained quantum wells obtained by a 6×6 Hamiltonian (including heavy hole, light hole and spin-orbit splitting band), optical gain and radiative current density are calculated for the strained quantum well laser structures. The compressive strain in the GaN well region strongly depresses the TM mode optical gain and enhances the TE mode optical gain.

Fan W. J.;Li M. F.;Chong T. C.;Xia J. B.

Solid State Communications

1996

A voltage-controlled tunable two-color infrared detector with photovoltaic (PV) and photoconductive (PC) dual-mode operation at 3-5 μm and 8-14 μm using GaAs/AlAs/AlGaAs double barrier quantum wells (DBQWs) and bound-to-continuum GaAs/AlGaAs quantum wells is demonstrated. The photoresponse peak of the photovoltaic GaAs/AlAs/GaAlAs DBQWs is at 5.3 μm, and that of the photoconductive GaAs/GaAlAs quantum wells is at 9.0 μm. When the two-color detector is under a zero bias, the spectral response at 5.3 μm is close to saturate and the peak detectivity at 80 K can reach 1.0×1011 cmHz1/2/W, while the spectral photoresponsivity at 9.0 μm is absolutely zero completely. When the external voltage of the two-color detector is changed to 2.0 V, the spectral photoresponsivity at 5.3 μm becomes zero while the spectral photoresponsivity at 9.0 μm increases comparable to that at 5.3 μm under zero bias, and the peak detectivity (9.0 μm) at 80 K can reach 1.5×1010 cmHz1/2/W. Strictly speaking, this is a real bias-controlled tunable two-color infrared photodetector. We have proposed a model based on the PV and PC dual-mode operation of stacked two-color QWIPs and the effects of tunneling resonance with narrow energy width of photoexcited electrons in DBQWs, which can explain qualitatively the voltage-controlled tunable behavior of the photoresponse of the two-color infrared photodetector. © 1996 American Institute of Physics.

Zhang Yaohui;Jiang D. S.;Xia J. B.;Cui L. Q.;Song C. Y.;Zhou Z. Q.;Ge W. K.

Applied Physics Letters

1996

A numerical analysis of a quantum directional coupler based on II-shaped electron waveguides is presented with use of the scattering-matrix method. After the optimization of the device parameters, uniform output for the two output ports and high directivity are obtained within a wide range of the electron momenta. The electron transfer in the device is found more efficient than that in the previously proposed structures. The study of the shape-dependence of transmission for the device shows that the device structure with smooth boundaries exhibits a much better performance.

Sheng Wei-Dong;Xia Jian-Bai

Applied Physics A Materials Science and Processing

1997

The one-dimensional energy bands and corresponding conductivities of a T-shaped quantum-dot superlattice are studied in various cases: different periods, with potential barriers between dots, and in transverse electric fields. It is found that the conductivity of the superlattices has a similar energy relation to the conductance of a single quantum dot, but vanishes in the energy gap region. The energy band of a superlattice with periodically modulated conducting width in the perpendicular magnetic field is calculated for comparison with magneto-transport experiments. It is found that due to the edge state effect the electron has strong quantum transport features. The energy gaps change with the width of the channel, corresponding to the deep peaks in the conductance curve. This method of calculating the energy bands of quantum-dot superlattices is applicable to complex geometric structures without substantial difficulty. © 1997 American Institute of Physics.

Xia Jian-Bai;Sheng Wei-Dong

Journal of Applied Physics

1997

Within the framework of the single-band effective-mass envelope-function theory, the effect of electric field on the electronic structures of pyramidal quantum dot is investigated. Taking the Coulomb interaction between the heavy holes and electron into account, the quantum confined Stark shift of the exciton as functions of the strength and direction of applied electric field and the size of the quantum dot are obtained. An interesting asymmetry of Stark shifts around the zero field is found. © 1997 Elsevier Science Ltd.

Chang Kai;Xia Jian-Bai

Solid State Communications

1997

In this paper, we propose the periodic boundary condition which can be applied to a variety of semiconductor nanostructures to overcome the difficulty of solving Schrodinger equation under the natural boundary condition. When the barrier width is large enough, the average of the maximum and minimum of energy band under the periodic boundary condition is very close to the energy level obtained under the natural boundary condition. As an example, we take the GaAs/Ga1-xAlxAs system. If the width of the Ga1-xAlxAs barrier is 200 Å , the average of the maximum and minimum of energy band of the GaAs/Ga1-xAlxAs superlattices is very close to the energy level of the GaAs/Ga1-xAlxAs quantum wells (QWs). We give the electronic structure effective mass calculation of T-shaped quantum wires (T-QWRs) under the periodic boundary condition. The lateral confinement energies E1D-2Dof electrons and holes, the energy difference between T-QWRs and QWs, are precisely determined. © 1997 by Allerton Press, Inc.

Li Shu-Shen;Xia Jian-Bai

Chinese Physics Letters

1997