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1.
光子晶体多量子阱中的谱线分裂 总被引:6,自引:1,他引:5
用时域有限差分法研究了一维光子晶体多量子阱中的谱线分裂现象,揭示了光子隧穿多量子阱时谱线分裂的规律性.研究发现,谱线分裂是阱间相互耦合的结果,其特征不仅取决于势阱的个数,而且与垒区和阱区的几何参量密切相关.计算结果表明,对称多量子阱结构中,光子隧穿p个势阱时,单阱对应的每条透射谱线会分裂为p条,各分裂谱线互不交叠.这样在有限的禁带区域可以成倍增加光子束缚态,使信道密度最大化,光波有效带宽的使用最优化,有望在光通信超密集波分复用和光学精密测量中获得广泛应用. 相似文献
2.
D. A. Grützmacher T. O. Sedgwick A. Zaslavsky A. R. Powell R. A. Kiehl W. Ziegler J. Cotte 《Journal of Electronic Materials》1993,22(3):303-308
First structural and electrical data are reported for SiGe/Si quantum well structures grown by a new ultra clean low temperature
epitaxial deposition process at atmospheric pressure. It is found that the process suppresses the segregation of germanium,
possibly by a chemical termination of the surface during the growth. Mutiple-quantum-well structures with controllable well
widths and abrupt interfaces have been prepared at temperatures ranging from 550 to 650°C. Magneto-transport measurements
of modulation doped quantum wells reveal hole mobilities of 2000 cm2/Vs at 4.2 K at a carrier density of 1.7*1012 cm−2 and a germanium concentration of 18% in the SiGe channel. Resonant tunneling diodes grown by this technique exhibit well
resolved regions of negative differential resistance within a very symmetric I-V characteristic. 相似文献
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4.
用Matlab程序语言数值计算了多量子阱结构的能级,并研究了量子阱间耦合对其带结构的影响。多量子阱模型是在一个一维有限深势阱(阱边势垒高为 V0)中插入等高(Vb)等厚(b)的势垒方式建成,被分割而成的多量子阱厚度为w。通过增加插入壁垒的个数N、改变阱垒厚度比w/b 及势垒高度比V0/Vb,分别近似计算了对应的结构的能级及波函数。计算结果显示,量子阱间耦合受上述参数的强烈影响,改变参数N,w/b 或V0/Vb ,能带和带隙的宽度是可以被调节的。研究说明,量子阱的能带及带隙宽度达到期望值是完全有可能实现的。 相似文献
5.
Low-temperature photoluminescence from disordered SiGe/Si quantum wells and quantum wires made from periodic quantum wells
by electron beam lithography and reactive ion etching has been measured. No enhancement in luminescence is seen, compared
to that in periodic quantum wells, in the disordered wells or quantum wires. New transitions are observed in the wire luminescence,
including a possible no-phonon transition exhibiting a 32 meV blue shift compared to the same transition in the wells. 相似文献
6.
L. Sun D. H. Zhang H. Q. Zheng S. F. Yoon C. H. Kam 《Materials Science in Semiconductor Processing》2001,4(6)
This paper reports characterization of n-type strained InGaAsP/InP multiple quantum well (MQW) structures, grown by solid source molecular beam epitaxy (MBE), using high-resolution X-ray diffraction. It was found that well-defined periodic satellite peaks up to 20 orders and the Pendellösung fringes appeared between the satellite peaks were observable, indicating a very high crystalline quality of the MQW structures. The data extracted from the rocking curves, including position and FWHM of the zero-order peak, the angle separation between diffraction peaks and the intensity of the first-order peak, indicate that high-quality InGaAsP/InP MQW structures with controllable well width and sharp interfaces can be successfully grown using all solid sources, and the well width has no significant effect on the quality of the interfaces. These observations are in good agreement with the simulated results using dynamical X-ray theory. 相似文献
7.
J. M. Ballingall Pin Ho P. A. Martin G. J. Tessmer T. H. Yu N. Lewis E. L. Hall 《Journal of Electronic Materials》1990,19(6):509-513
Growth and characterization results are presented for pseudomorphic high electron mobility transistor structures with InxGa1-xAs single quantum well and GaAs(h
1)In
x
Ga1−x
As(h
2) thin strained superlattice active layers where 0.25≤x ≤ 0.4. All of the samples were grown by molecular beam epitaxy. Hall effect at 77 K, photoluminescence at 2 K, in-situ reflection
high energy electron diffraction, and transmission electron microscopy measurements are discussed. Critical layer thickness
measurements are compared with the Matthews-Blakeslee theory. Photoluminescence transition energies are compared with a self-consistent
solution to Schrodinger’s and Poisson’s equations. 相似文献
8.
S. J. Lycett A. J. Dewdney M. Ghisoni C. E. Norman R. Murray D. Sansom J. S. Roberts 《Journal of Electronic Materials》1995,24(3):197-202
We present the results of an investigation of impurity free vacancy diffusion (IFVD) post-growth treatments of p-i-n modulator structures. The investigation is in two parts. We first establish that gallium vacancies (VGa) are produced during IFVD (by measuring the intensity of the low temperature 1.2 eV signal from Si-VGa complexes) in a thick Si-doped GaAs sample. The second part of this work investigates the degree of intermixing of three 80Å GaAs quantum wells embedded in the intrinsic region of a p-i-n modulator at depths between 1–2 μm from the surface. Photoluminescence studies on etched samples and cathodoluminescence showed that no significant depth dependence occurs as a result of IFVD. 相似文献
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10.
2μm InGaSb/AlGaAsSb strained quantum wells and a tellurium-doped GaSb buffer layer were grown by molecular beam epitaxy(MBE).The growth parameters of strained quantum wells were optimized by AFM, XRD and PL at 77 K.The optimal growth temperature of quantum wells is 440℃.The PL peak wavelength of quantum wells at 300 K is 1.98μm,and the FWHM is 115 nm.Tellurium-doped GaSb buffer layers were optimized by Hall measurement.The optimal doping concentration is 1.127×1018 cm-3 and the resistivity is 5.295×10-3Ω·cm. 相似文献
11.
Spin splitting of conduction subbands in Al0.3Ga0.7As/GaAs/AlxGa1-xAs/Al0.3Ga0.7As step quantum wells induced by interface and electric field related Rashba effects is investigated theoretically by the method of finite difference.The dependence of the spin splitting on the electric field and the well structure,which is controlled by the well width and the step width,is investigated in detail.Without an external electric field,the spin splitting is induced by an interface related Rashba term due to the built-in structure inversion asymmetry.Applying the external electric field to the step QW,the Rashba effect can be enhanced or weakened,depending on the well structure as well as the direction and the magnitude of the electric field.The spin splitting is mainly controlled by the interface related Rashba term under a negative and a stronger positive electric field,and the contribution of the electric field related Rashba term dominates in a small range of a weaker positive electric field.A method to determine the interface parameter is proposed.The results show that the step QWs might be used as spin switches. 相似文献
12.
《Microelectronics Reliability》2015,55(1):62-65
The change of spectrum of the AlGaAs/GaAs single quantum well laser diode is measured under the application of uniform uniaxial in-plane tensile and compressive stress. In the range of the tensile stress we apply (up to 597 MPa), the wavelength increases linearly at a rate of 5.3 nm GPa−1. The energy band gap decreases with the tensile stress with the slope of −10 meV GPa−1, which is close to the theoretical change of the heavy hole band edge with respect to the conduction band edge. There is a shorter wavelength peak existing on the spectrum as the tensile stress increases, suggesting a transition from the conduction band to a higher energy valence band. For the compressive stress (up to −516 MPa), the wavelength decreases with the stress, but it shows an abrupt reduction from −162 to −200 MPa. The threshold current also varies as a result of the change of the energy band structure. 相似文献
13.
Spin splitting of conduction subbands in Al0.3Ga0.7As/GaAs/AlxGa1-xAs/Al0.3Gaa7As step quantum wells induced by interface and electric field related Rashba effects is investigated theoretically by the method of finite difference. The dependence of the spin splitting on the electric field and the well structure, which is controlled by the well width and the step width, is investigated in detail. Without an external electric field, the spin splitting is induced by an in terface related Rashba term due to the built-in structure inversion asymmetry. Applying the external electric field to the step QW, the Rashba effect can be enhanced or weakened, depending on the well structure as well as the direction and the magnitude of the electric field. The spin splitting is mainly controlled by the interface related Rashba term under a negative and a stronger positive electric field, and the contribution of the electric field related Rashba term dominates in a small range of a weaker positive electric field. A method to determine the interface parameter is proposed. The results show that the step QWs might be used as spin switches. 相似文献
14.
This article puts forward a new method in calculating the band structures of low-dimensional semiconductor structures.In this study,the valence band structures of InAs/GaAs quantum ring and lens-shaped quantum dot are calculated with four-band model,in the framework of effective-mass envelope function theory.To determine the Hamiltonian matrix elements,this article develops the numerical Fourier transform method instead of the widely used analytical integral method.The valence band mixing is considered.The ... 相似文献
15.
T. S. Moise L. J. Guido J. C. Beggy T. J. Cunningham S. Seshadri R. C. Barker 《Journal of Electronic Materials》1992,21(1):119-124
Data presented here demonstrate that strained-layer (111)B Al0.15Ga0.85As-In0.04Ga0.96As quantum wells exhibit unique optical properties when compared to otherwise identical (100) oriented strained layers. Photoluminescence
measurements identify a strain-induced electric field of order 6.7 Vμm-1 within the (111)B quantum well that is not present for the (100) case. Photoluminescence excitation spectroscopy measurements
show that the heavy-hole to light-hole energy band splitting is approximately 7 meV larger for the (111)B structure than for
the (100) structure.
Howard Hughes Doctoral Fellow
IBM Graduate Fellow 相似文献
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18.
The optical emission characteristics of biaxially compressed InAs
x
P1−
x
/InP strained single quantum well (QW) structures, with nominal compositionx=0.67, have been investigated using photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies. The highly
strained QWs exhibit intense and narrow PL in the 0.9–1.5 μm wavelength range, similar to the lattice-matched InGaAs(P)/InP
system. The 20 K PLE spectra exhibit well-resolved features attributed ton=1 heavy hole (E1H1) and light hole (E1L1) transitions in the 1.0–1.5 μm wavelength range. In addition, features attributed
to transitions betweenn=2 electrons and heavy holes (E2H2), and betweenn=1 electrons and unconfined holes (E1Hf), were observed. The energy splitting between the heavy-hole and light-hole bands
was found to be a sensitive measure of the band offsets in the system. The best prediction of this splitting was obtained
for a valence band offset of δE
V
∼0.25δE
G
. This value of band offset was in agreement with the energy position of the E1Hf transition. The observed transition energies
were also compared with the results of a finite square well model, taking into account the effects of strain, and the results
offer further support for the band offset assignment. This study indicates that the InAsP system may be advantageous for application
in strained-layer optoelectronic devices operating in the 1.3–1.6 μm wavelength range. 相似文献
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20.
The abruptness of hetero-interfaces in InGaN multiple quantum well structures is shown to degrade when a high temperature
growth follows growth of the multiple quantum well (MQW) region, as is generally required for the growth of full device structures.
We have analyzed MQW samples both with and without high temperature GaN “cap” layers, using x-ray diffraction (XRD), grazing
incidence x-ray reflection (GIXR), and photoluminescence. While all of these techniques indicate a degradation of the MQW
structure when it is followed by growth at high temperature, GIXR is shown to be especially sensitive to changes of heterointerface
abruptness. GIXR measurements indicate that the heterojunctions are less abrupt in samples that have high temperature cap
layers, as compared to samples with no cap layer. Furthermore, the degree of roughening is found to increase with the duration
of growth of the high temperature cap layer. The degradation of the heterointerfaces is also accompanied by a reduction in
the intensity of satellite peaks in the x-ray diffraction spectrum. 相似文献