- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Role of Sb on the vertical-alignment of type-II strain-coupled InAs/GaAsSb multi quantum dots structures
摘要： The implementation of GaAs0.8Sb0.2 as CL to obtain type-II strain-coupled InAs MQD structures has been examined and compared to similar structures without Sb or without strain coupling. First, it has been demonstrated that capping with GaAsSb prevents the formation of In-rich agglomerations that hampered the QD formation as it has been observed in the sample without Sb. Instead, it promotes the vertical alignment (VA) of almost all QDs with a high density of QD columns. Second, there is a preferential Sb accumulation over the dots together with an undulation of the growth front, contrary to the observed in the uncoupled structure. In case of a deficient covering of GaAsSb, as occurs for giant QDs, In-rich agglomerations may develop. Each VAQD column consists of a sequence of alternating quantum blocks of pyramid-shaped In(Ga)As separated by GaAsSb blocks that rest over them. These Sb-rich blocks are not homogeneous accumulating around the pyramidal apex like a collar. Between the columns, there is an impoverishment of In and Sb compared to the uncoupled sample. These columns can behave as self-aligned nanowires with type II band alignment between self-assembled InAs and GaAsSb quantum blocks that opens new opportunities for novel devices.
关键词： GaAsSb capping layer,III-V semiconductors alloys,Transmission electron microscopy,Composition distribution,Vertical aligned quantum dots
更新于2025-09-23 15:21:01
-
Scalable Compact Modeling of III-V DHBTs: Prospective Figures of Merit Toward Terahertz Operation
摘要： We investigate the bias, temperature, and frequency dependence of two III–V double heterojunction bipolar transistors technologies based on InGaAs/InP and GaAsSb/InP processes, using a HiCuM/L2 compact model-based multigeometry scalable parameter extraction methodology. Very good agreement between the model simulations and experimental data is demonstrated. Transistor currents and junction capacitances show very good scaling, thereby allowing the separation of intrinsic and peripheral effects. Prediction of future III–V HBT technologies figures-of-merit is performed by using the generated scalable model card.
关键词： InGaAs/InP DHBTs,heterojunction bipolar transistors,Compact model,GaAsSb/InP DHBTs
更新于2025-09-23 15:21:01
-
Size and Shape Evolution of GaAsSb-Capped InAs/GaAs Quantum Dots: Dependence on the Sb Content
摘要： Capping InAs/GaAs quantum dots (QDs) with a thin GaAsSb layer alters the QDs structural properties, leading to considerable changes in their optical properties. The increase of the Sb content induces a redshift of the emission energies, indicating a change in the buried QDs shape and size. The presence of well-defined ground- and excited-state emission bands in all the photoluminescence spectra allow an accurate estimation of the buried QDs size and shape by numerical evaluation and tuning of the theoretical emission energies. For an Sb content below 14%, the QDs are found to have a type I band alignment with a truncated height pyramidal form. However, for higher Sb content (22%), the QDs are present in a full pyramidal shape. The observed behavior is interpreted in terms of increasing prevention of InAs QDs decomposition with increasing the Sb content in the cap layer.
关键词： size,GaAsSb,InAs quantum dots,modeling,shape
更新于2025-09-19 17:13:59
-
<i>In situ</i> passivation of GaAsSb nanowires for enhanced infrared photoresponse
摘要： Surface passivation of semiconductor nanowires (NWs) is important for their optoelectronic properties and applications. Here, the in situ passivation effect of an epitaxial InP shell and the corresponding photodetector performance is experimentally studied. Compared with the unpassivated GaAsxSb1-x core-only NWs, the GaAsxSb1-x/InP core/shell NWs have shown much stronger photoluminescence and cathodoluminescence intensities. Correspondingly, the fabricated single GaAsxSb1-x/InP core/shell NW photodetector shows a responsivity of 325.1 A/W (@ 1.3 μm and 1.5 V) that is significantly enhanced compared to that of single GaAsxSb1-x core-only NW photodetectors (143.5 A/W), with a comparable detectivity of 4.7×1010 and 5.3×1010 cm√Hz/W, respectively. This is ascribed to the enhanced carrier mobility and carrier concentration by the in situ passivation, which lead to both higher photoconductivity and dark-conductivity. Our results show that in situ passivation is an effective approach for performance enhancement of GaAs1-xSbx NW based optoelectronic devices.
关键词： semiconductor,surface passivation,infrared photodetector,GaAsSb,MOCVD,InP,nanowire
更新于2025-09-19 17:13:59
-
European Microscopy Congress 2016: Proceedings || FIB patterning for position-controlled nanowire growth
摘要： Semiconductor nanowire (NW) based heterostructures are a promising material system for next generation optoelectronic devices, such as flexible solar cells and light emitting diodes [1]. Their reduced contact area and surface strain relaxation allow for epitaxial growth on lattice-mismatched substrates, a key advantage for integration of different III-V semiconductors with existing silicon-based technology. Position-controlled NWs can be grown in ordered arrays on Si to improve uniformity and device integration. This is commonly performed by using a SiO2 thin film as a mask. Patterning of circular holes in the mask (Fig. 1(a)) allows for site-specific NW growth in predefined patterns and positions. To date, this is performed using lithography techniques such as electron beam lithography or nanoimprint lithography [2]. Important processing parameters include oxide thickness, hole diameter and pattern pitch, requiring several steps to be optimized in order to achieve a high yield of uniform NWs [3]. Additionally, the catalytic particle is rarely centered in the hole, leading to undesirable asymmetry in the NW cross-sections [4]. In this work, the parameter space for direct patterning of NW growth substrates by focused ion beam (FIB) is explored (Fig. 1). Self-catalyzed GaAsSb NWs were grown using molecular beam epitaxy (MBE) on a FIB patterned Si(111) substrate with 40 nm thermal oxide, where hole size, dose and Ga-beam overlap were systematically varied (Fig. 1(a-c)). It is expected that a higher degree of flexibility and control can be attained using FIB compared to the conventionally used resist-based patterning techniques. In addition, patterning by FIB leads to Ga implantation in both Si and SiO2, which could positively affect the self-catalyzed NW growth and the properties of the NW-substrate system in a unique way. After MBE growth, three distinct growth regimes can be recognized, present in all arrays (Fig. 1(d-e)): The smallest (10 nm pattern) diameter row features a high yield (≤ 80%) of straight NWs. As the hole diameter increases there is initially a transition to more parasitic crystal growth and finally multiple (2-5) NWs grow within each hole. As the dose increases between arrays in each column, the patterned diameter for these transitions decreases proportionally. The results demonstrate that using FIB the parameter space can be mapped out efficiently within a single growth session and that growth can be tuned between aligned single NWs, 2D parasitic crystals and multiple NWs per hole. Transmission electron microscopy and electrical testing of single NWs directly on the growth substrate [5] will be used to refine the structural analysis and study the electrical properties of these NWs. It is expected that in addition to the flexibility of FIB patterning, III-V NWs grown on FIB-patterned Si will exhibit novel properties due to the implantation of Ga and the altered NW-substrate interface.
关键词： self-catalyzed,nanowires,focused ion beam,nanostructuring,GaAsSb
更新于2025-09-11 14:15:04
-
Optical properties of quasi-type-II structure in GaAs/GaAsSb/GaAs coaxial single quantum-well nanowires
摘要： The GaAsSb-based quantum well plays a very important role in optoelectronic devices due to its excellent wavelength tunability. When the dimension reduces, the quantum con?nement effect will take place and the quantum well in nanowires will show many interesting characteristics. GaAsSb-based quantum-well nanowires are of contemporary interest. However, the properties of the quasi-type-II structure in a single quantum well nanowire have been rarely investigated. Here, we grow GaAs/GaAs0.92Sb0.08/GaAs coaxial single quantum-well nanowires and discussed their power-dependent and temperature-dependent photoluminescence. We ?nd that due to the small band offset of conduction bands, both type-I like and type-II like emission exist in our nanowires. When electrons obtain enough thermal energy through collisions or surrounding environment, they will overcome the barrier and diffuse to the GaAs conduction band, which contributes to the type-II like recombination. These results show the optical property of the quasi-type-II quantum well in nanowires, which can pave the way toward future nanoscale quantum well devices.
关键词： GaAsSb,quasi-type-II structure,photoluminescence,quantum well,nanowires
更新于2025-09-09 09:28:46
-
[IEEE 2018 IEEE Symposium on VLSI Technology - Honolulu, HI (2018.6.18-2018.6.22)] 2018 IEEE Symposium on VLSI Technology - Record 47 mV/dec top-down vertical nanowire InGaAs/GaAsSb tunnel FETs
摘要： Pocketed vertical nanowire InGaAs/GaAsSb tunnel FETs (TFET) with sub-threshold swing (SS) reaching 47 mV/dec are demonstrated. The achieved sub-threshold performance is the steepest reported so far for a top-down TFET in the III-V material system. Smooth vertical wires with diameters as narrow as 30 nm are achieved using a CH4 based dry etch process. Drive current at 0.35 V supply voltage approaches 0.7 μA/μm for a fixed Ioff of 1 nA/μm.
关键词： tunnel FETs,InGaAs/GaAsSb,vertical nanowire,sub-threshold swing,III-V material system
更新于2025-09-04 15:30:14
-
[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || Wavefunctions and Optical Gain in $$ \text{In}_{0.3} {\text{Ga}}_{0.7} {\text{As}}/{\text{GaAs}}_{0.4} {\text{Sb}}_{0.6} $$In0.3Ga0.7As/GaAs0.4Sb0.6 Type-II Double Quantum Well Nanoheterostructure Under External Uniaxial Strain
摘要： Variations in wavefunction con?nement under external uniaxial strain are observed to affect the optical gain obtained in type-II quantum well nanodimension heterostructures. This paper reports the wavefunctions and optical gain realized in In0.3Ga0.7As/GaAs0.4Sb0.6 type-II double QW heterostructure under uniaxial strain along [001]. Energy bands, wavefunctions of con?nement states in the structure and optical gain of the heterostructure under electromagnetic ?eld perturbation are presented. The 6×6 k·p Hamiltonian matrix is considered, and Luttinger–Kohn model has been applied for the electronic band structure calculations. Optical gain spectra of the double QW nanoheterostructure under external uniaxial strain of 1, 2 and 5 GPa, respectively, is calculated. The optical gain curve shows a signi?cant improvement in gain under external uniaxial strain along [001] at 300 K. For a charge carrier injection of 8 × 1012/cm2, the optical gain is 9170 in x polarization. The heterostructure is seen to be operating in the energy range of 0.65–0.8 eV (1549–1907 nm). Thus, a wide range wavelength tuning can be realized.
关键词： Heterostructure,InGaAs,GaAsSb,Optical gain,Type-II
更新于2025-09-04 15:30:14