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1.
研究了双子带占据的In0.52Al0.48As/In0.53Ga0 .47As单量子阱中磁电阻的Shubnikov-de Haas(SdH)振荡效应和霍耳效应,获得了不 同子带电子的浓度、迁移率、有效质量和能级位置.低磁感应强度(B<1.5T)下由迁移率谱和 多载流子拟合相结合的方法得到的各子带电子浓度与通过SdH振荡得到的结果一致.在d 2ρ/dB2-1/B的快速傅里叶变换
关键词:
InAlAs/InGaAs单量子阱
SdH振荡
二维电子气
磁致子带间散射 相似文献
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用Shubnikov-de Haas(SdH)振荡效应,研究了在1.4 K下不同量子阱宽度(10—35 nm)的InP基高电子迁移率晶体管材料的二维电子气特性.通过对纵向电阻SdH振荡的快速傅里叶变换分析,得到不同阱宽时量子阱中二维电子气各子带电子浓度和量子迁移率.研究发现,在Si掺杂浓度一定时,阱宽的改变对于量子阱中总的载流子浓度改变不大,但是随着阱宽的增加,阱中的电子从占据一个子带到占据两个子带,且第二子带上的载流子迁移率远大于第一子带迁移率.当量子阱宽度为20 nm时,处在第二子能级上的电子数与处在
关键词:
量子阱宽
二维电子气
Shubnikov-de Haas振荡
高电子迁移率晶体管 相似文献
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研究了基于InP基的In0.65Ga0.35As/In0.52Al0.48As赝型高迁移率晶体管材料中纵向磁电阻的Shubnikov-de Haas(SdH)振荡效应和霍耳效应,通过对纵向磁电阻SdH振荡的快速傅里叶变换分析,获得了各子带电子的浓度,并因此求得了各子带能级相对于费米能级的位置.联立求解Schrdinger方程和Poisson方程,自洽计算了样品的导带形状、载流子浓度分布以及各子带能级和费米能级位置.理论计算和实验结果很好符合.实验和理论计算均表明,势垒层的掺杂电子几乎全部转移到了量子阱中,转移率在95%以上.
关键词:
SdH振荡
二维电子气
FFT分析
自洽计算 相似文献
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通过低温和强磁场下的磁输运测量研究了Al0.22Ga0.78N/GaN调制掺杂异质结构中2DEG的子带占据性质和子带输运性质.在该异质结构的磁阻振荡中观察到了双子带占据现象,并发现2DEG的总浓度随第二子带浓度的变化呈线性关系.得到了该异质结构中第二子带被2DEG占据的阈值电子浓度为7.3×1012cm-2.采用迁移率谱技术得到了不同样品的分别对应于第一和第二子带的输运迁移率.发现当样品产生应变弛豫时第一子带的电子迁移
关键词:
AlGaN/GaN异质结
二维电子气
子带占据
输运迁移率 相似文献
6.
主要研究具有倒置能带结构的n-HgTe/HgCdTe第三类量子阱Shubnikov-de Haas(SdH)振荡中的拍频现象.发现在量子阱中电子存在强烈的Rashba自旋分裂,通过对SdH振荡进行三种不同方法的分析:SdH振荡对1/B关系的快速傅里叶变换、SdH振荡中拍频节点分析和对SdH振荡拍频数值拟合,得到了完全一致的电子Rashba自旋分裂能量(28—36 meV).
关键词:
n-HgTe/HgCdTe
Shubnikov-de Haas振荡
Rashba自旋分裂 相似文献
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为研究磷化铟高电子迁移率晶体管(InP HEMT)外延结构材料的抗电子辐照加固设计的效果,本文采用气态源分子束外延法制备了系列InP HEMT外延结构材料.针对不同外延结构材料开展了1.5 MeV电子束辐照试验,在辐照注量为2×1015 cm-2条件下,并测试了InP HEMT外延结构材料二维电子气辐照前后的电学特性,获得了辐照前后不同外延结构InP HEMT材料二维电子气归一化浓度和电子迁移率随外延参数的变化规律,分析了InP HEMT二维电子气辐射损伤与Si-δ掺杂浓度、InGaAs沟道厚度和沟道In组分以及隔离层厚度等结构参数的关系.结果表明:Si-δ掺杂浓度越大,隔离层厚度较薄,InGaAs沟道厚度较大,沟道In组分低的InP HEMT外延结构二维电子气辐射损伤相对较低,具有更强的抗电子辐照能力.经分析原因如下:1)电子束与材料晶格发生能量传递,破坏晶格完整性,且在沟道异质界面引入辐射诱导缺陷,增加复合中心密度,散射增强导致二维电子气迁移率和浓度降低;2)高浓度Si-δ掺杂和薄隔离层有利于提高量子阱二维电子气浓度,降低二维电子气受辐射... 相似文献
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W. Z. Shen W. G. Tang S. C. Shen S. M. Wang T. Anderson 《International Journal of Infrared and Millimeter Waves》1994,15(10):1643-1650
The influence of the GaAs cap layer thickness on the luminescence properties in strained In0.20Ga0.80As/GaAs single quantum well (SQW) structures has been investigated using temperature-dependent photoluminescence (PL) spectroscopy. The luminescence peak is shifted to lower energy as the GaAs cap layer thickness decreases, which demonstrates the effect of the GaAs cap layer thickness on the strain of InGaAs/GaAs single quantum wells (SQW). We find the PL quenching mechanism is the thermal activation of electron hole pairs from the wells into the GaAs cap layer for the samples with thicker GaAs cap layer, while in sample with thinner GaAs cap layer exciton trapping on misfit dislocations is dominated. 相似文献
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《Superlattices and Microstructures》2001,29(1):51-55
The effect of properly lined-up quantum-well (QW) states, under an external bias, on the electron resonant tunneling is investigated in an InAlAs/InGaAs triple-barrier structure. The degree of alignment of two QW confined ground states at a resonant voltage is analyzed with low-temperature measurement. The experimental data shows the enhanced resonant tunneling effects, and proves that the second QW structure added to the InGaAs/ InAlAs double-barrier heterostructure can act as an effective tool for probing and extracting the resonant tunneling properties deep in a QW. 相似文献
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《Superlattices and Microstructures》1998,23(2):253-259
In this paper photoluminescence measurements at low temperature under different excitation powers were carried out on an InGaAs tensile strained (x = 0.3) quantum well with InGaAs barriers lattice matched (LM) to InP. Evidence of a type-II recombination was found between carriers confined in the tensile layer and in the LM layer. This study allows us to deduce an accurate determination of the conduction band offset in the In0.3Ga0.7As/In0.53Ga0.47As/InP system. Moreover, we include the previous type-II structure between InAlAs barriers in order to confine both electrons and holes. This structure has potential applications in electro-optical modulators. We simulate its optical modulation by solving the Schrödinger equation using the envelope function approximation and calculating the absorption spectrum taking into account excitonic effects. 相似文献
14.
K. Požela A. Šilėnas J. Požela V. Jucienė G. B. Galiev J. S. Vasil’evskii E. A. Klimov 《Applied Physics A: Materials Science & Processing》2012,109(1):233-237
The alternating change of electron mobility values in the modulation doped InAlAs/InGaAs/InAlAs quantum well (QW) dependently on a thickness of the InAs layer inserted in the center of the QW is theoretically predicted and experimentally observed. The electron mobility enhancement by a factor of 1.5–2 takes place when the 4 nm-thick InAs layer is inserted into the 17 nm-width QW. The experimental maximal value of the electron drift velocity at the threshold electric field for intervalley electron scattering achieves (1.8?2)×107 cm/s and does not nearly depend on the thickness of the InAs insert. The high value of maximal drift velocity is conserved at the additional doping of the InAs insert up to electron density of 4×1012 cm?2 in the QW. 相似文献
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Abstract The results of electrical transport measurements (Hall effect and resistivity) performed on In.65Ga.35As-In Al.48 As modulation doped heterostructure (with Si-doped InAlAs donor layer) and on In .52Al .48As thick layer are presented as a function of temperature (77–300K range) and hydrostatic pressure (up to 1300 MPa). At low temperature, the persistent photoconductivity (PPC) and metastable donor states occupation effects were observed. Due to the pressure induced decrease of the two-dimensional electron gas concentration the pronounced increase in the amplitude of observed effects was obtained. The above results are discussed in terms of DX-like centers and/or interface/surface states in the QW structure. 相似文献
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L. Bouzaiene S. Rekaya H. Sghaier L. Sfaxi H. Maaref 《Applied Physics A: Materials Science & Processing》2005,80(2):295-299
We have calculated the low-temperature electron density in a -doped AlGaAs/InGaAs/GaAs heterostructure in the presence of a piezoelectric field. Growth of a strained InGaAs layer on (N11) GaAs substrates causes a piezoelectric field to be built into the quantum well of a pseudomorphic high electron mobility transistor (HEMT). The presence of this field modifies the electronic properties of strained-layer heterostructures. A self-consistent analysis is made of these -doping systems to solve simultaneously the Schrödinger and Poisson equations taking into account exchange-correlation and strain effects. Thus, we have found the confining potential, the electron density, the subband energies, the eigenenvelope wavefunctions, and the Fermi-energy level in the quantum well. We have studied the effects of the InGaAs channel width and the indium composition on the electron density. Our results show a larger increase of the electron density when the calculated value is for a (111) GaAs substrate rather than for equivalent (001) and (311) substrates. We have also investigated the effects of the environmental Al concentration seen by the Si -doped on the electron density. PACS 71.76 相似文献
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YIN Tao DU Jinyu LIAN Peng XU Zuntu CHEN Changhua GUO Weiling LIU Ying LI Shuang GAO Guo ZOU Deshu CHEN Jianxin SHEN Guangdi 《Chinese Journal of Lasers》1999,8(5):397-401
1lntroductionCarhan,aIVcolutnnelement,hasmanyadvantagesinGaAsAlGaAsmaterials,suchasIowdiffudricoefficient,relativelowactivateenergyabout26meV,highincmptiOnconcentratboandhighm0bilityduetothelowcomensaterate.SocarbonhasbeenwidelyusedinGaAsAlGaAsheter0unctionbipoartransistors(HBT),modulationdoPingfieldeffecttransistors(m),tunneldiodes,iInPurityinducedlayerdisorderinglaserdiodeS,anddistributedBraggreflectors(DBRs)intheverticalcavitysurfaceedrittinglasers(VCSEL).Ingeneral,therearesever… 相似文献
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YIN Tao DU Jinyu LIAN Peng XU Zuntu CHEN Changhua GUO Weiling LIU Ying LI Shuang GAO Guo ZOU Deshu CHEN Jianxin SHEN Guangdi MA Xiaoyu CHEN Lianghui 《中国光学快报(英文版)》1999,8(5)
By low-pressure metalorganic chemical vapor deposition (LP-MOCVD) system,InGaAs/AlGaAs graded-index separate-confinement heterostructure strained quantum well lasers are grown with carbon doped the upper cladding layer and the capping layer. Carbon tetracholride (CCl4) is used as the carbon source. 100 μm oxide stripe lasers are fabricated,and the laser output power per facet (uncoated) reaches 1.2 W with 2A injection current under the room temperature continuous wave (CW) operation. The threshold current density is 150 A/cm2 with 1000 μm cavity length. The slope efficiency per facet reaches 0.53W/A,and the total external differential quantum efficiency is above 85%. The relations between the threshold current densities,the differential quantum efficiency and the cavity length are studied. 相似文献
19.
T. H. Chen Y. S. Huang T. S. Shou K. K. Tiong D. Y. Lin F. H. Pollak M. S. Goorsky D. C. Streit M. Wojtowicz 《Physica E: Low-dimensional Systems and Nanostructures》2000,8(4)
We have characterized the properties of three AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor structures with two different well widths fabricated by molecular beam epitaxy on (0 0 1) GaAs substrates with different threading dislocation densities using room temperature photoreflectance (PR) and photoluminescence (PL). The samples were denoted as A, B and C with well widths of 140, 160 and 160 Å, respectively. Samples A and B were grown on substrates with lower threading dislocation densities. For samples B and C, the well width exceeds the pseudomorphic limit so that there is some strain relaxation and related misfit dislocations, as determined from X-ray measurements. In order to detect the anisotropic strain of the misfit dislocations related to strain relaxation, the PR measurements were performed for incident light polarized along [1 1 0] and
directions. Evidence for the influence of the strain relaxation upon the relaxed channel was provided by the observed anisotropy of the polarized PR features and reduction of the intensity of PL signals in the InGaAs channel layer. The lowest lying intersubband transition has been confirmed by a comparison of the PR and PL spectra. Signals have been observed from every region of the sample making it possible to evaluate the In and Al compositions, channel width and two-dimensional electron gas density as well as the properties of the GaAs/AlGaAs multiple quantum well buffer layer. 相似文献
20.
In this study, we investigate the effects of GaN cap layer thickness on the two-dimensional electron gas (2DEG) electron density and 2DEG electron mobility of AlN/GaN heterostructures by using the temperature-dependent Hall measurement and theoretical fitting method. The results of our analysis clearly indicate that the GaN cap layer thickness of an AlN/GaN heterostructure has influences on the 2DEG electron density and the electron mobility. For the AlN/GaN heterostructures with a 3-nm AlN barrier layer, the optimized thickness of the GaN cap layer is around 4 nm and the strained a-axis lattice constant of the AlN barrier layer is less than that of GaN. 相似文献