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1.
AlSb/InAs quantum well (QW) structures and InAs films on GaAs (001) substrates were grown by molecular beam epitaxy (MBE). We investigated the dependence of electron mobility and two-dimensional electron gas (2DEG) concentration on the thickness of an InAs channel. It is found that electron mobility as high as 19050 cm2·V-1·s-1 has been achieved for an InAs channel of 22.5 nm. The Hall devices with high sensitivity and good temperature stability were fabricated based on the AlSb/InAs QW structures. Their sensitivity is markedly superior to Hall devices of InAs films. 相似文献
2.
3.
Yu. N. Khanin E. E. Vdovin S. V. Dubonos A. Levin L. Eaves M. Henini 《JETP Letters》2005,82(8):526-531
The electron transport is studied in split-gate structures fabricated on the basis of a modulation-doped heterostructure that contains a single quantum well and self-assembled InAs quantum dots near the 2D electron gas regions. The current passing through the channel with a denumerable set of InAs quantum dots is found to exhibit Coulomb oscillations as a function of the gate voltage. The oscillations are associated with the excited p states of InAs quantum dots, which are characterized by opposite spins and caused by lifting of the spin degeneracy of the p state due to the Coulomb interaction. The Coulomb oscillations of the current are observed up to a temperature of ~20 K. The Coulomb energy is found to be ΔEc = 12.5 meV, which agrees well with the theoretical estimates for the p states of quantum dots in the structures under study. 相似文献
4.
D. V. Denisov I. T. Serenkov V. I. Sakharov G. É. Tsyrlin V. M. Ustinov 《Physics of the Solid State》2003,45(11):2194-2202
The formation of heteroepitaxial structures with InAs nanoclusters in an Si matrix during molecular-beam epitaxy and variations in the parameters of these structures due to thermal annealing are investigated by reflection high-energy electron diffraction (RHEED), medium-energy ion scattering (MEIS), and scanning electron microscopy (SEM). It is demonstrated that the deposition of InAs onto the Si(100) surface at certain temperatures brings about the formation of tetrahedral nanopyramids with {111} orientation of the lateral faces. It is revealed that InAs nanoislands can be epitaxially overgrown with silicon, which leads to gradual smoothing of the three-dimensional relief. After annealing under vacuum, the Si/InAs/Si(100) structures are stable at tem-peratures up to 700°C. 相似文献
5.
利用微芯片制备技术制备了带有电极的原位电学薄膜芯片,并结合自制的原位透射电镜样品台,实现了低温下透射电子显微镜聚焦电子束对InAs纳米线的精细刻蚀以及不同温度下的原位电学性能测量.研究发现,随着刻蚀区域截面积的减小,纳米线的电导率也随之减小.当纳米线的截面积从大于10000 nm2刻蚀至约800 nm2时,纳米线电导的减小速率与截面积的减小具有线性关系.同时利用低温聚焦电子束刻蚀,在InAs纳米线上原位制备了一个10 nm的纳米点,并在77与300 K下对该纳米点进行了电学性能测量.通过测量发现在77 K时出现库仑阻塞效应,发生了电子隧穿现象;而300 K时,热扰动提供的能量使这种现象消失. 相似文献
6.
利用自组织生长InAs/GaAs量子点的垂直相关排列机制,生长了上下两层用6.5nm GaAs间隔的InAs结构.下层InAs已经成岛,由于应力传递效应,上层InAs由二维生长向三维成岛生长的转变提前发生,临界厚度从1.7ML变成小于1.5ML.透射电子显微镜截面象显示形成上下两层高度差别很大的InAs量子点,但是由于两层量子点之间存在强烈的电子耦合,光致发光谱中只有与包含大量子点的InAs层相对应的一个发光峰. 相似文献
7.
We describe fabrication methods of GaAs and InAs quantum dot (QD) structures and related semiconductor nanostructures having nanoscale heterointerfaces grown by the selective area metalorganic vapor-phase epitaxial (SA-MOVPE) method on partially masked GaAs substrates. GaAs QD arrays and wire–dot coupled structures having strong lateral confinement were fabricated on appropriately designed masked substrates. InAs QDs were also formed on various kinds of GaAs pyramidal and wire structures, where site-selective formation is demonstrated by the combination of self-assembling growth mode and selective area growth. The application of QDs to single-electron transistors using SA-MOVPE is also described. 相似文献
8.
T. Schweizer K. Köhler P. Ganser A. Hülsmann P. Tasker 《Applied Physics A: Materials Science & Processing》1991,53(2):109-113
Modulation doped Al0.3Ga0.7As/In
x
Ga1–x
As/GaAs high electron mobility transistor structures for device application have been grown using molecular beam epitaxy. Initially the critical layer thickness for InAs mole fractions up to 0.5 was investigated. For InAs mole fractions up to 0.35 good agreement with theoretical considerations was observed. For higher InAs mole fractions disagreement occurred due to a strong decrease of the critical layer thickness. The carrier concentration for Al0.3Ga0.7As/In
x
Ga1–x
As/GaAs high electron mobility transistor structures with a constant In
x
Ga1–x
As quantum well width was investigated as a function of InAs mole fraction. If the In
x
Ga1–x
As quantum well width is grown at the critical layer thickness the maximum carrier concentration is obtained for an InAs mole fraction of 0.37. A considerable higher carrier concentration in comparison to single-sided -doped structures was obtained for the structures with -doping on both sides of the In
x
Ga1–x
As quantum well. Al0.3Ga0.7As/In
x
Ga1–x
As/GaAs high electron mobility transistor structures with InAs mole fractions in the range 0–0.35 were fabricated for device application. For the presented field effect transistors best device performance was obtained for InAs mole fractions in the range 0.25–0.3. For the field effect transistors with an InAs mole fraction of 0.25 and a gate length of 0.15 m a f
T of 115 GHz was measured.Dedicated to H.-J. Queisser on the occasion of his 60th birthday 相似文献
9.
Hong Chen J.A. Peters Yue Pan J.J. Heremans N. Goel S.J. Chung M.B. Santos W. Van Roy G. Borghs 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):374
Spin–orbit interaction in two-dimensional electron systems can lead to a spin-dependent reflection of carriers off a lithographic barrier. Scattering of a spin-unpolarized beam from the barrier leads to the creation of two fully spin-polarized side beams in addition to an unpolarized specularly reflected beam. We experimentally demonstrate a method to create spin-polarized beams of ballistic electrons in mesoscopic samples fabricated on InSb/InAlSb and InAs/AlGaSb heterostructures. We describe two geometries, one open and one closed, in which the spin-dependent reflection and spin-dependent semiclassical trajectories were observed. 相似文献
10.
K.S. Joo S.H. Chun J.Y. Lim J.D. Song J.Y. Chang 《Physica E: Low-dimensional Systems and Nanostructures》2008,40(9):2874-2878
The large electron mobility at room temperature and the absence of Schottky barrier to metals make InAs two-dimensional electron gas (2DEG) a good candidate for SPIN-FET (FET—field-effect-transistor) applications. So far the growth was done either on the InAlAs epilayers compositionally matched to InP substrates, or on Sb-based compound semiconductors. Here we aim to grow InAs 2DEG on GaAs substrates by using a strain-relaxing buffer layer. We introduce In0.4Al0.6As glue layer to the metamorphic structure and investigate the physical properties of InAlAs/InGaAs multi-quantum-well (MQW) structures via X-ray diffraction, transmission electron microscopy, and photoluminescence. We find that the use of As dimer instead of tetramer and the choice of proper growth temperature are essential for successful growth. InAs-inserted-channel InAlAs/InGaAs inverted high-electron-mobility transistor (HEMT) structures show promising results for SPIN-FET application. 相似文献
11.
用分子束外延技术将高灵敏度的InAs/AlSb量子阱结构的Hall器件赝配生长在GaAs衬底上。设计了由双δ掺杂构成的Hall器件的新结构,有效地提高了器件的面电子浓度。与传统的没有掺杂的InAs/AlSb量子阱结构的Hall器件相比,室温下器件电子迁移率从15 000 cm2·V-1·s-1 提高到16 000 cm2·V-1·s-1。AFM测试表明材料有好的表面形态和结晶质量。从77 K 到300 K对Hall器件进行霍尔测试,结果显示器件不同温度范围有不同散射机构。双δ掺杂结构形成高灵敏度、高二维电子气(2DEG)浓度的InAs/AlSb异质结Hall器件具有广阔的应用前景。 相似文献
12.
M. V. Maximov A. F. Tsatsul'nikov B. V. Volovik D. A. Bedarev A. E. Zhukov A. R. Kovsh N. A. Maleev V. M. Ustinov P. S. Kop'ev Zh. I. Alferov R. Heitz N. N. Ledentsov D. Bimberg 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
We have studied quantum dots (QDs) fabricated by activated spinodal decomposition (ASD) of an InGa(Al)As alloy deposited on top of self-organized InAs nanoscale stressors on GaAs substrate. Such a growth sequence results in a strong red shift of the PL emission down to 1.3 μm at 300 K. This red shift is caused by the formation of In-rich areas in the vicinity of the InAs islands, which increase the effective dot size. Beyond a certain critical InAs composition or nominal thickness of the InGa(Al)As layer the PL line shifts back towards higher energies. Adding Al to the alloy increases the red shift for a given In concentration. Room temperature lasing near 1.3 μm with threshold current densities of about 85 A/cm2 was achieved for lasers based on three-fold stacked ASD-formed QDs, with a maximum cw output power of 2.7 W. 相似文献
13.
《Comptes Rendus Physique》2008,9(8):788-803
Single quantum dots (QDs) have great potential as building blocks for quantum information processing devices. However, one of the major difficulties in the fabrication of such devices is the placement of a single dot at a pre-determined position in the device structure, for example, in the centre of a photonic cavity. In this article we review some recent investigations in the site-controlled growth of InAs QDs on GaAs by molecular beam epitaxy. The method we use is ex-situ patterning of the GaAs substrate by electron beam lithography and conventional wet or dry etching techniques to form shallow pits in the surface which then determine the nucleation site of an InAs dot. This method is easily scalable and can be incorporated with marker structures to enable simple post-growth lithographic alignment of devices to each site-controlled dot. We demonstrate good site-control for arrays with up to 10 micron spacing between patterned sites, with no dots nucleating between the sites. We discuss the mechanism and the effect of pattern size, InAs deposition amount and growth conditions on this site-control method. Finally we discuss the photoluminescence from these dots and highlight the remaining challenges for this technique. To cite this article: P. Atkinson et al., C. R. Physique 9 (2008). 相似文献
14.
D. Schuh J. Bauer E. Uccelli R. Schulz A. Kress F. Hofbauer J.J. Finley G. Abstreiter 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):72
We report on a new approach for positioning of self-assembled InAs quantum dots on (1 1 0) GaAs with nanometer precision. By combining self-assembly of quantum dots with molecular beam epitaxy on in situ cleaved surfaces (cleaved-edge overgrowth) we have successfully fabricated arrays of long-range ordered InAs quantum dots. Both atomic force microscopy and micro-photoluminescence measurements demonstrate the ability to control position and ordering of the quantum dots with epitaxial precision as well as size and size homogeneity. Furthermore, photoluminescence investigations on dot ensembles and on single dots confirm the high homogeneity and the excellent optical quality of the quantum dots fabricated. 相似文献
15.
Cross-sectional Scanning Tunneling Microscopy (X-STM) is an ideal tool to study the structural properties of semiconductor nanostructures, such as InAs self-assembled quantum dots (QDs) and the properties of individual doping atoms at the atomic scale. The technique allows for a precise determination of the size, shape and composition of overgrown semiconductor nanostructures which can be part of a (complex) multilayer structure. In this paper we discuss our recent results on InAs QD structures that were capped by various methods in order to control their size and shape. We will show that the capping process does strongly affect the final QD structure and thus forms a very important step in the dot formation process. Recently people have started to investigate magnetically doped QDs. We have used our X-STM technique to study the incorporation of single Mn-impurities in InAs/GaAs QDs. 相似文献
16.
E. E. Vdovin Yu. N. Khanin P. L. Shabel’nikova A. Levin L. Eaves S. V. Dubonos M. Henini 《Journal of Experimental and Theoretical Physics》2007,105(1):145-148
The paper presents the results obtained in a study of electron transport in split-gate structures prepared from heterostructures with self-organizing InAs quantum dots situated close to a two-dimensional electron gas. Coulomb oscillations of current through InAs quantum dots depending on the voltage on the gate were observed. Coulomb current oscillations persisted up to about 20 K. The Coulomb energy ΔE C = 12.5 meV corresponding to theoretical estimates for the p-states of quantum dots in our structures was determined. 相似文献
17.
The three semiconductors InAs, GaSb, and AlSb form an approximately lattice-matched set around 6.1 Å, covering a wide range of energy gaps and other properties. Of particular interest are heterostructures combining InAs with one or both of the antimonides, and they are emphasized in this review. In addition to their use in conventional device types (FETs, RTDs, etc.), several heterostructure configurations with unique properties have been explored, especially InAs/AlSb quantum wells and InAs/GaSb superlattices.InAs/AlSb quantum wells are an ideal medium to study the low-temperature transport properties in InAs itself. With gate-induced electron sheet concentrations on the order 1012 cm−2, they exhibit a pronounced conductivity quantization. The very deep wells (1.35 eV) provide excellent electron confinement, and also permit modulation doping up to at least 1013 electrons cm−2. Because of the very low effective mass in InAs, heavily doped wells are essentially metals, with Fermi energies around 200 meV, and Fermi velocities exceeding 108 cm s−1. Contacted with superconducting electrodes, such structures can act as superconductive weak links.InAs/GaSb-related superlattices with their broken-gap lineup behave like semimetals at large lattice periods, but if the lattice period is shortened, increasing quantization effects cause a transition to a narrow-gap semiconductor, making such structures of interest for infrared detectors, often combined with the deliberate addition of strain. 相似文献
18.
We report a resonant tunnelling diode (RTD) small signal equivalent circuit model consisting of quantum capacitance and quantum inductance. The model is verified through the actual InAs/In0.53Ga0.47As/AlAs RTD fabricated on an InP substrate. Model parameters are extracted by fitting the equivalent circuit model with ac measurement data in three different regions of RTD current-voltage (I-V) characteristics. The electron lifetime, representing the average time that the carriers remain in the quasibound states during the tunnelling process, is also calculated to be 2.09ps. 相似文献
19.
We present atomistic theory of electronic and optical properties of a single InAs quantum dot grown on a pyramidal InP nanotemplate. The shape and size of the dot is assumed to follow the nanotemplate shape and size. The electron and valence hole single particle states are calculated using atomistic effective–bond–orbital model with second nearest-neighbor interactions. The electronic calculations are coupled to separately calculated strain distribution via Bir–Pikus Hamiltonian. The optical properties of InAs dots embedded in InP pyramids are calculated by solving the many-exciton Hamiltonian for interacting electron and hole complexes using the configuration–interaction method. The effect of quantum-dot geometry on the optical spectra is investigated by a comparison between dots of different shapes. 相似文献
20.
通过广义梯度近似的第一原理全电子相对论计算, 研究了不同界面类型InAs/GaSb超晶格的界面结构、电子和光吸收特性. 由于四原子界面的复杂性和低对称性, 通过对InAs/GaSb超晶格进行电子总能量和应力最小化来确定弛豫界面的结构参数. 计算了InSb, GaAs型界面和非特殊界面(二者交替)超晶格的能带结构和光吸收谱, 考察了超晶格界面层原子发生弛豫的影响.为了证实能带结构的计算结果, 用局域密度近似和Hartree-Fock泛函的平面波方法进行了计算. 对不同界面类型InAs/GaSb超晶格的能带结构计算结果进行了比较, 发现界面Sb原子的化学键和离子性对InAs/GaSb超晶格的界面结构、 能带结构和光学特性起着至关重要的作用. 相似文献