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本文通过对含有高In组分量子点的双波长LED进行了模拟计算, 并对器件的能带结构、载流子浓度、复合速率和辐射光谱进行了研究. 通过对器件结构的调整与对比, 发现蓝绿双波长LED的绿光量子阱中加入高In组分量子点后可以拓宽辐射光谱, 使LED光谱具有更高的显色指数, 为实现无荧光粉的白光LED提供指导. 量子点对载流子具有很强的束缚能力, 并且载流子在量子点处具有更短的寿命, 载流子优先在量子点处复合, 量子点处所对应的黄光与量子阱润湿层所对应的绿光的比例随量子点浓度的增大而增大, 载流子浓度较低时以量子点处的黄光辐射为主, 载流子浓度变大后, 量子点复合逐渐达到饱和, 绿光辐射开始占据主导. 对间隔层厚度和间隔层掺杂浓度的调节可以很方便地调控载流子的分布, 从而实现对含有量子点的双波长LED两个活性层辐射速率的调控. 结果表明, 通过对量子点浓度、间隔层厚度、间隔层掺杂浓度的控节可以很好地实现对LED辐射光谱的调控作用.
关键词:
GaN
量子点
光谱调控
双波长LED 相似文献
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A new mechanism of transitions of an electronic system from the ground state to states with excitation energies exceeding many times the energy of a light photon initiating the transitions has been considered. This mechanism is based on the so-called optical “trampoline” effect: one of the interacting electrons receives energy from another electron and, simultaneously absorbing a photon ?ω, overcomes the energy gap significantly exceeding ?ω. Ionization of deep quantum wells by low-frequency light of moderate intensity due to the optical trampoline effect was calculated. 相似文献
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D. K. Loginov E. V. Ubyĭvovk Yu. P. Efimov V. V. Petrov S. A. Eliseev Yu. K. Dolgikh I. V. Ignat’ev V. P. Kochereshko A. V. Sel’kin 《Physics of the Solid State》2006,48(11):2100-2108
The optical reflection spectra of semiconductor GaAs/AlGaAs structures with wide quantum wells are studied experimentally. A theoretical analysis of the spectra is performed in terms of the exciton-polariton model in the approximation of quantum confinement of the exciton center of mass with regard to the contributions of both heavy and light excitons to the crystal polarization. The applicability range of the theory of the center-of-mass confinement for GaAs/AlGaAs heterostructures is estimated. It is established that, for quantum wells more than 180 nm wide, the interference effects observed in the reflection spectra of polariton waves are reproduced, to a good accuracy, by theoretical calculations based on the quantum confinement of the exciton center of mass. For quantum-well widths less than 150 nm, the experimental results are described better by the model of quantum confinement of electrons and holes. 相似文献
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A scattering process modeled by an imaginary potential V
I in the wide well of an asymmetric double quantum well structure (DQWS) is used to model the electron tunneling from the narrow well. Taking V
I –5 meV, the ground resonant level lifetimes of the narrow well in the DQWS are in quantitative agreement with the experimental resonance and non-resonance tunneling times. The corresponding scattering time 66 fs is much faster than the intersubband scattering time of LO-photon emission. 相似文献
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《Physics letters. A》2020,384(8):126185
The formation of the different structures of islands of electron-hole liquid in the quantum well is studied in a statistical model. The interaction between the islands of electron-hole liquid is considered by influencing of neighboring islands through exciton gas around the considered island. Two restricted regions were studied: an infinite strip and a disk. The theory gives the possibility to determine the probability of different states realization and to find the most probable state. The dependence of the radius, mutual positions of the electron-hole liquid islands, the number of the islands in the disk on the pumping, temperature and parameters of the system (the size and the shape) are calculated. 相似文献
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In this report, we designed a light emitting diode (LED) structure in which an N-polar p-GaN layer is grown on top of Ga-polar In0.1Ga0.9N/GaN quantum wells (QWs) on an n-GaN layer. Numerical simulation reveals that the large polarization field at the polarity inversion interface induces a potential barrier in the conduction band, which can block electron overflow out of the QWs. Compared with a conventional LED structure with an Al0.2Ga0.8N electron blocking layer (EBL), the proposed LED structure shows much lower electron current leakage, higher hole injection, and a significant improvement in the internal quantum efficiency (IQE). These results suggest that the polarization induced barrier (PIB) is more effective than the AlGaN EBL in suppressing electron overflow and improving hole transport in GaN-based LEDs. 相似文献
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D. K. Loginov 《Physics of the Solid State》2010,52(1):70-78
A theoretical model has been developed to describe the behavior of exciton polaritons in a wide quantum well for structures
with the zinc blende symmetry in a transverse magnetic field (the Voigt geometry). The model takes into account the mixing
of the 1s-1s and 1s-2p states of heavy excitons by the magnetic field and makes it possible to explain and quantitatively describe the activation
of optically inactive states in the reflection spectra and the magnetic-field-induced increase in the translational mass of
the exciton. The quantitative calculations of the spectra have been preformed using typical parameters for CdTe/ZnCdTe quantum-well
structures. 相似文献
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The optical polarization properties of staggered AlGaN-AlGaN/AlN quantum wells (QWs) are investigated using the theoretical model based on the k·p method. The numerical results show that the energy level order and coupling relation of the valence subband structure change in the staggered QWs and the trend is beneficial to TE polarized transition compared to that of conventional AlGaN/AlN QWs. As a result, the staggered QWs have much stronger TE-polarized emission than conventional AlGaN-based QWs, which can enhance the surface emission of deep ultraviolet (DUV) light-emitting diodes (LEDs). The polarization control by using staggered QWs can be applied in high efficiency DUV AlGaN-based LEDs. 相似文献
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《Superlattices and Microstructures》1995,17(1):35-39
Theoretical study of resonant tunneling is carried out in rectangular triple-barrier structures with C-type deep wells. Analytical expressions for the transmission coefficient and the resonance conditions are derived. Transmission characteristics versus electron energy are investigated and it is shown analytically that the transmission spectrum is a Lorentzian in form near energies of resonance. It is confirmed that the resonance energy is almost equal to the eigenenergy of the double-well structure. Moreover, wave functions of an electron at the resonance level are examined and the confining phenomenon is studied. 相似文献
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The absorption of light by free charge carriers with the participation of surface and bulk optical phonons is considered in terms of the Boltzmann statistics and Pekar-Fröhlich Hamiltonian for the electron-photon interaction in a polar semiconductor layer within the framework of the model of a rectangular quantum well. It is found that the contributions of the surface and bulk modes to the probability of light absorption depend on the quantum-well width. It is demonstrated that the line of the photon-phonon resonance has a complex structure due to the difference between the frequencies of the bulk and surface optical vibrations. The influence of the adjacent media on the coefficient of light absorption is investigated. 相似文献
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《Superlattices and Microstructures》1987,3(3):283-285
Resonant tunneling through an (AlGa)As/InXGa1−XAs/(AlGa)As double barrier structure has been observed. Three crystals with indium concentration x=0, x=0.08 and x=0.13 were grown. For x=0, GaAs wells, we investigated the variation in resonance voltage, i.e. voltage at peak current, between different diodes across a wafer. The resonance voltage exhibited a skew distribution which is interpreted as an effect of lateral alloy variation in the active layers and differences in contact resistance. For (InGa)Asv quantum wells we found a negative differential resistance at 77 K with a peak-to-valley ratio as large as 3:1. The resonance voltage decreased as the indium concentration x was increased. This is an effect of the position of the ground state which is lowered (due to smaller bandgap) compared to the Fermi level. At x=0.13 the ground state was found to be below the conduction band edge of the GaAs contact regions and therefore the ground state resonance was absent. 相似文献
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The multi-well energy representation technique is presented for the analysis of the valence band structures of multiple quantum
well (MQW) lasers. In terms of this technique and its relative formulae, calculations are performed for InGaAs/InGaAsP strained
MQW structures. It is found that the coupling exists between the wells, and causes the energy split. So, on the basis of the
computed results, the coupling between the wells is analysed, and the split of both the quantized energy levels at the Γ point
and the quantized energy bands at the non-Γ points is described. It is also found that the structural parameters of the MQW
system strongly influence the coupling property and the energy split, and hence these effects are also discussed in relation
to the periodic length, the well width, the distance between the wells, and the ratio of the well width to the periodic length.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Tight-binding calculations of the subband structures of zincblende-semiconductor [001] quantum wells
The scattering-theoretic T-matrix method is used to calculate the subband structures of GaAs?ZnSe and ZnSe?ZnSxSe1?x [001] quantum wells within an empirical tight-binding model, that includes the bulk Г6, Г7 and Г8 valence- and conduction bands. The resulting confinement energies for vanishing lateral crystal momentumk ‖ are compared with those, that are obtained from a simple effective mass model and effects are found and predicted which the effective mass model cannot account for. The effect of the band nonparabolicity and the influence of the microscopic sequence of atomic layers, which determines the symmetry properties of a quantum well, are studied for the GaAs?ZnSe wells. 相似文献