2019年12月25日星期三

Fabrication of thin body InAs-on-insulator structures by Smart Cut method with H+ implantation at room temperature

This paper demonstrates the fabrication of InAs-on-insulator (InAs-OI) structures with high crystallinity using the Smart Cut process, which combinates direct wafer bonding with a wafer splitting process by implanted H+. Controlling the implantation dose and rate allows us to produce wafer-level InAs-OI structures on Si substrates by H+ implantation at room temperature, which can be performed in standard implantation equipment. It is found that (111) InAs-OI has a much flatter surface after splitting than (100) one. After thinning by using CMP and wet etching, 15 nm thick InAs-OI structures are realized with the high thickness uniformity.


Source:IOPscience

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2019年12月18日星期三

Gate-induced transition between metal-type and thermally activated transport in self-catalyzed MBE-grown InAs nanowires

Electronic transport properties of InAs nanowires are studied systematically. The nanowires are grown by molecular beam epitaxy on a SiOx-covered GaAs wafer, without using foreign catalyst particles. Room-temperature measurements revealed relatively high resistivity and low carrier concentration values, which correlate with the low background doping obtained by our growth method. Transport parameters, such as resistivity, mobility, and carrier concentration, show a relatively large spread that is attributed to variations in surface conditions. For some nanowires the conductivity has a metal-type dependence on temperature, i.e. decreasing with decreasing temperature, while other nanowires show the opposite temperature behavior, i.e. temperature-activated characteristics. An applied gate voltage in a field-effect transistor configuration can switch between the two types of behavior. The effect is explained by the presence of barriers formed by potential fluctuations.

Source:IOPscience

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2019年12月11日星期三

Current-injected light emission of epitaxially grown InAs/InP quantum dots on directly bonded InP/Si substrate

Current-injected light emission was confirmed for metal organic vapor phase epitaxy (MOVPE) grown (Ga)InAs/InP quantum dots (QDs) on directly bonded InP/Si substrate. The InP/Si substrate was prepared by directly bonding of InP thin film and a Si substrate using a wet-etching and annealing process. A p–i–n LED structure including Stranski–Krastanov (Ga)InAs/InP QDs was grown by MOVPE on an InP/Si substrate. No debonding between Si substrate and InP layer was observed, even after MOVPE growth and operation of the device under continuous wave conditions at RT. The photoluminescence, current/voltage, and electroluminescence characteristics of the device grown on the InP/Si substrate were compared with reference grown on an InP substrate.

Source:IOPscience

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2019年12月4日星期三

Investigation of Wafer-Bonded InAs/Si Heterojunction by Transmission Electron Microscopy

An InAs/Si heterojunction formed by a wet wafer bonding method with an annealing temperature of 350 °C was investigated by transmission electron microscopy (TEM). InAs and Si were observed to be uniformly bonded without any voids in a 2-µm-long field of view in a bright-field TEM image. A high-resolution TEM image revealed that, between the InAs and Si lattice images, there existed a transition layer having an amorphous-like structure 10–12 nm thick, which had the role of atomically combining the two crystals. The transition layer was separated into two layers of different brightnesses in a high-angle annular dark-field scanning TEM image. The distributions of In, As, Si, and O atoms in the vicinity of the heterointerface were examined by energy dispersive X-ray spectroscopy. The amounts of In, As, and Si atoms gradually changed within a 20-nm-thick intermediate layer including the transition layer. Accumulated O atoms were detected in the transition layer.

Source:IOPscience

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2019年11月27日星期三

High-Temperature 1.3 µm InAs/GaAs Quantum Dot Lasers on Si Substrates Fabricated by Wafer Bonding

We present 1.3 µm InAs/GaAs quantum dot lasers on Si substrates operating at high temperatures. Our lasers are fabricated through epitaxial growth on GaAs substrates of the InAs/GaAs quantum dot laser double heterostructure, and subsequent GaAs/Si wafer bonding and layer transfer onto Si substrates. Both of the on-Si lasers by direct- and metal-mediated bonding exhibit lasing temperatures over 100 °C. Partial p-type doping in the InAs/GaAs quantum dot core layer is found to significantly increase the characteristics temperature T0. This result verifies the suitability of III–V quantum dot lasers as a light source in Si photonic integrated circuits.


Source:IOPscience

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2019年11月20日星期三

Dry etching of deep air holes in GaAs/AlGaAs-based epi-wafer having InAs quantum dots for fabrication of photonic crystal laser

Photonic crystal (PhC) structures are often fabricated on epi-wafers with a heterostructure to realize various micro- or nanophotonic devices by dry etching processes. We discuss the dry etching process for a GaAs/AlGaAs-based epi-wafer using a resist mask to fabricate a proposed PhC laser. The epi-wafer has multiple stacked layers of InAs quantum dots (QDs) with a high density of 6 × 1010 cm−2, which cause the reduction of the diameter of the etched air holes. A higher density and more stacked layers of QDs intensify the reduction effect. By enhancing the physical etching effect, the verticality of the profile of the air holes etched in the epi-wafer with a five stacked InAs QD layers is greatly improved. The results show that the improved etching conditions make it feasible to fabricate the proposed PhC laser structure.

Source:IOPscience

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2019年11月11日星期一

Uniform and position-controlled InAs nanowires on 2'' Si substrates for transistor applications

This study presents a novel approach for indirect integration of InAs nanowires on 2'' Si substrates. We have investigated and developed epitaxial growth of InAs nanowires on 2'' Si substrates via the introduction of a thin yet high-quality InAs epitaxial layer grown by metalorganic vapor phase epitaxy. We demonstrate well-aligned nanowire growth including precise position and diameter control across the full wafer using very thin epitaxial layers (<300 nm). Statistical analysis results performed on the grown nanowires across the 2'' wafer size verifies our full control on the grown nanowire with 100% growth yield. From the crystallographic viewpoint, these InAs nanowires are predominantly of wurtzite structure. Furthermore, we show one possible device application of the aforementioned structure in vertical wrap-gated field-effect transistor geometry. The vertically aligned InAs nanowires are utilized as transistor channels and the InAs epitaxial layer is employed as the source contact. A high uniformity of the device characteristics for numerous transistors is further presented and RF characterization of these devices demonstrates an ft of 9.8 GHz.

Source:IOPscience

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2019年11月6日星期三

Room temperature contactless electroreflectance characterization of InGaAs/InAs/GaAs quantum dot wafers

Contactless electroreflectance (CER) mapping has been performed on InGaAs capped InAs/GaAs quantum dot (QD) wafers of 2 inch diameter grown by molecular beam epitaxy. The CER spectra have revealed several features related to InAs self-assembled QDs and a quantum well (QW) formed of the InAs wetting layer and the InGaAs cap layer. The particular optical transitions have been identified based on theoretical calculations of the energy levels in the InAs/InGaAs/GaAs wetting layer related step-like QW, performed within the effective mass approximation. The influence of possible uncertainties in cap content or band offsets has also been analysed. The advantages of modulation spectroscopy, namely its absorption-like character and high sensitivity to optical transitions with even very low oscillator strength including those between the excited states, have allowed the energies of all the transitions along the wafer to be followed. The latter has shown that within experimental error the transition energies are independent of the position of the probing spot on the sample. It demonstrates not only a very high uniformity of the dot ensemble but also the wetting layer related QW and hence also the content and thickness of the InGaAs cap.

Source:IOPscience

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2019年10月30日星期三

Wafer-bonded coupled multilayer cavity with InAs quantum dots for two-color emission

A GaAs/AlAs coupled multilayer cavity structure with InAs quantum dots (QDs) was fabricated by wafer-bonding of two cavity structures grown individually. The wafer-bonding technique is important to control the spatial distribution of nonlinear polarization for strong terahertz emission by the differential frequency generation of the two cavity modes of the coupled cavity. Three layers of self-assembled InAs QDs were inserted in a cavity grown on a (001) GaAs substrate as optical gain materials for two-color emission of the cavity mode lights. The other cavity with a GaAs cavity layer was grown on a (113)B GaAs substrate. Two-color emissions with a 3.8 THz frequency difference were successfully observed from the wafer-bonded coupled cavity by cw optical pumping at room temperature.

Source:IOPscience


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2019年8月22日星期四

High performance InAs/GaAsSb superlattice long wavelength infrared photo-detectors grown on InAs substrates

We demonstrated high performance long wavelength InAs/GaAs0.09Sb0.91 type-II superlattices infrared photo-detectors grown on InAs substrates. Superlattices photodiodes with InAs layer thickness from 14 to 24 ML showed 50% cutoff wavelength from 6 to 12.5 μm while the lattice-mismatch was kept smaller than 4.0 × 10−4 without any additional interface layers for strain balance. Quantum efficiency spectra showed oscillating characteristics which were attributed to the plasma effect in the highly doped InAs buffer layers. The absorption coefficient of 1800 cm−1 and diffusion length of 10 μm of minority carriers in the SLs on InAs have been obtained through simulation. A photodiode exhibited a 12.5 μm cutoff wavelength with a peak detectivity of 7.4 × 1010 cm Hz1/2 W−1 and 2.6 × 1011 cm Hz1/2 W−1 at 76 K and 52 K, respectively.


Source:IOPscience

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2019年8月9日星期五

Free-Standing InAs/InGaAs Microtubes and Microspirals on InAs (100)

A new material system for creating InAs-based free-standing micro- and nanoobjects is proposed. For the first time, InAs/InGaAs microtubes and microspirals were obtained, including tubes containing two-dimensional electron gas, ordered arrays of tubes, and tubes protruding over the substrate edge. First measurements of the electrical conductivity of InAs/InGaAs microtubes were performed.



Source:IOPscience


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2019年8月1日星期四

Growth and characterization of InAs layers obtained by liquid phase epitaxy from Bi solvents

In this paper, we report the first liquid phase epitaxial growth of InAs epitaxial layers using 100% Bi solvent. At a growth temperature of 470 °C, the layers are macroscopically mirror like and the obtained growth rate is ~40 nm min−1. High-resolution XRD measurements reveal perfect lattice matching between the layer and the substrate, very good structural quality of the layers and less than 0.07% content of substitutional Bi in the layer. Raman spectra from background-doped layers are indicative of carrier concentration near the epilayer surface of less than 1016 cm−3, while assessment of these layers by means of infrared reflectance spectroscopy points to carrier concentration in the bulk of the layers of the order of 1 × 1015 cm−3. 4 K photoluminescence spectra from the same layers exhibit excitonic lines with half-widths 3 meV, which is a signature for electron concentration comparable to the known critical Mott density in InAs of ~5 × 1014 cm−3. We attribute the low background doping of the epitaxial layers to the low dissolution in Bi of Si and other residual impurities at 470 °C.



Source:IOPscience

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2019年7月23日星期二

Optical characterization of InAs film grown on SnO2substrate by the electrodeposition technique

Indium arsenide films have been grown by an electrodeposition process at low temperature on a tin oxide (SnO2) substrate. X-ray diffraction studies showed that the as-grown films are poorly crystallized and heat treatment improved the crystallinity of InAs films. Atomic force microscopic measurements revealed that the InAs film surface is formed by particles for which the grain size depends on the electrolysis parameters; we have found that the grain size increases with the electrolysis current density. Absorption measurements show that the band gap energy red-shifts with increasing particle size. This result can be interpreted as a consequence of the quantum confinement effect on the carriers in the nanocrystallites.



Source:IOPscience

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2019年7月17日星期三

Growth of InAs on micro- and nano-scale patterned GaAs(001) substrates by molecular beam epitaxy

Molecular beam epitaxy of InAs on micro- and nano-scale patterned GaAs(001) substrates was studied. An InAs epilayer grown on the micro-scale patterned substrate exhibits islands with {1 1 3}-type facets, and is similar to that grown on the flat (unpatterned) substrate. In contrast, the preferred growth of InAs on the nano-scale patterned substrate is in the \langle 001\rangle  direction and exhibits islands with {1 1 0}-type facets. The thickness of the dense dislocation networks at the interface due to strain relaxation is reduced by the micro-scale pattern in comparison with the flat substrate, while for growth on the nano-scale patterned substrate, the strain relaxes via the formation of stacking faults more than dislocations. X-ray diffraction reveals that the strains in the 300 nm InAs epilayers are nearly fully relaxed, and the patterns tend to decrease the lattice constants of the epilayer, implying mass transport of Ga atoms into the epilayer from the GaAs substrates.


Source:IOPscience

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2019年7月9日星期二

Estimation of doping density in low doped n-InAs by electrolyte-based capacitance-voltage measurements in the deep depletion mode

Doping density profiling in InAs is difficult due to lack of good quality Schottky contacts and the narrow bandgap nature of the material. The electrolyte can be used to form a Schottky-like contact but the inversion layer formation does not allow obtaining a dopant concentration in low doped InAs. To overcome this issue, a pulse CV technique has been implemented to drive a sample into the deep depletion mode which makes it possible to use the depletion approximation to calculate a carrier concentration. The measured capacitance-voltage characteristics were compared with the simulation and showed good agreement with it.



Source:IOPscience

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2019年7月5日星期五

Photoluminescence study of low density InAs quantum clusters grown by molecular beam epitaxy

We report a systematic optical spectroscopy study of low density InAs quantum clusters (QCs) grown by molecular beam epitaxy. The photoluminescence (PL) spectra show emission features of a wetting layer (WL) which contains hybridized quantum well states. The low-energy tail of the QCs' PL profile is actually an ensemble of some sharp lines, originating from the emission of different exciton states (e.g. X, X*, XX*) in a single quasi-three-dimensional (Q3D) cluster as detailed in the micro-PL spectra. The temperature dependence of PL spectra indicates photocarrier distribution and transport in the QC–WL system. Furthermore, this small InAs Q3D cluster is integrated with a distributed Bragg reflector structure, and using optical excitation creates a single photon source with the second-order correlation function of g(2)(0) = 0.31 at 16 K.


Source:IOPscience


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2019年6月20日星期四

Shape and size control of InAs/InP (113)B quantum dots by Sb deposition during the capping procedure

he role of Sb atoms present on the growth front during capping of InAs/InP (113)B quantum dots (QDs) is investigated by cross-sectional scanning tunnelling microscopy, atomic force microscopy, and photoluminescence spectroscopy. Direct capping of InAs QDs by InP results in partial disassembly of InAs QDs due to the As/P exchange occurring at the surface. However, when Sb atoms are supplied to the growth surface before InP capping layer overgrowth, the QDs preserve their uncapped shape, indicating that QD decomposition is suppressed. When GaAs0.51Sb0.49 layers are deposited on the QDs, conformal growth is observed, despite the strain inhomogeneity existing at the growth front. This indicates that kinetics rather than the strain plays the major role during QD capping with Sb compounds. Thus Sb opens up a new way to control the shape of InAs QDs.


Source:IOPscience


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2019年6月14日星期五

Effects of growth temperature and metamorphic buffer on electron mobility of InAs film grown on Si substrate by molecular beam epitaxy

The growth of the InAs film directly on the Si substrate deflected from the plane (100) at 4° towards (110) has been performed using a two-step procedure. The effect of the growth and annealing temperature on the electron mobility and surface topography has been investigated for a set of samples. The results show that the highest electron mobility is  in the sample, in which the 10-nm InAs nucleation layer is grown at a low temperature of 320 °C followed by ramping up to 560 °C, and the nucleation layer was annealed for 15 min and the second layer of InAs is grown at 520 °C. The influence of different buffer layers on the electron mobility of the samples has also been investigated, which shows that the highest electron mobility of  at 300 K is obtained in the sample grown on a thick and linearly graded InGaAlAs metamorphic buffer layer deposited at 420 °C.



Source:IOPscience

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2019年6月5日星期三

GaAsSb layer thickness dependence of arsenic incorporation on InAs/GaAsSb superlattice on InAs substrate grown by metalorganic vapor phase epitaxy for mid-infrared device

We investigated the gas flow sequence to realize a short-period and lattice-matched InAs/GaAsSb superlattice on an InAs substrate by metalorganic vapor phase epitaxy (MOVPE) growth for applications in mid-infrared photonic devices. The arsenic composition of GaAsSb for lattice matching was adjusted by adding AsH3 flow to residual arsenic incorporation. The growth conditions for lattice-matched superlattices at a period of 5 nm were found. The superlattices with period thicknesses of 1 to 9 nm were successfully confirmed by the photoluminescence (PL) peak in the range from 2.4 to 5 µm depending on layer thickness at 20 K. The emission wavelength can be controlled by changing the layer thickness of superlattices. The results led to the improvement of InAs/GaAsSb type II superlattice growth.



Source:IOPscience

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2019年5月28日星期二

Wafer-bonded coupled multilayer cavity with InAs quantum dots for two-color emission

A GaAs/AlAs coupled multilayer cavity structure with InAs quantum dots (QDs) was fabricated by wafer-bonding of two cavity structures grown individually. The wafer-bonding technique is important to control the spatial distribution of nonlinear polarization for strong terahertz emission by the differential frequency generation of the two cavity modes of the coupled cavity. Three layers of self-assembled InAs QDs were inserted in a cavity grown on a (001) GaAs substrate as optical gain materials for two-color emission of the cavity mode lights. The other cavity with a GaAs cavity layer was grown on a (113)B GaAs substrate. Two-color emissions with a 3.8 THz frequency difference were successfully observed from the wafer-bonded coupled cavity by cw optical pumping at room temperature.


Source:IOPscience

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2019年5月23日星期四

Effect of the growth mode on the two- to three-dimensional transition of InAs grown on vicinal GaAs(001) substrates

Some differences were observed between conventional molecular-beam epitaxy (MBE) and mobility enhanced epitaxy (MEE) of InAs on a vicinal GaAs(001) substrate in the variation of the number density N of the InAs islands, with additional InAs coverage (θ−θc) after the critical InAs coverage θc during the two- to three-dimensional (2D–3D) transition. For MBE the variation was consistent with the power law N(θ)~(θ−θc)α; while for MEE, the linear relation N(\theta) \propto (\theta-\theta_{\mathrm {c}})  was observed. The difference is discussed in terms of the randomness in the nucleation of the InAs islands.


Source:IOPscience

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2019年5月9日星期四

InSb quantum dots for the mid-infrared spectral range grown on GaAs substrates using metamorphic InAs buffer layers

Type II InSb/InAs quantum dots (QDs) were successfully grown on GaAs substrates using three different metamorphic buffer layer (MBL) designs. The structural properties of the resulting metamorphic InAs buffer layers were studied and compared using cross-sectional transmission electron microscopy and high resolution x-ray diffraction measurements. Photoluminescence (PL) originating from the InSb QDs was observed from each of the samples and was found to be comparable to the PL of InSb QDs grown onto homo-epitaxially deposited InAs. The 4 K PL intensity and linewidth of InSb QDs grown onto a 3 µm thick InAs buffer layer directly deposited onto GaAs proved to be superior to that from QDs grown onto an InAs MBL using either AlSb or GaSb interlayers. Light-emitting diode structures containing ten layers of InSb QD in the active region were subsequently fabricated and electroluminescence from the QDs was obtained in the mid-infrared spectral range up to 180 K. This is the first step towards obtaining mid-infrared InSb QD light sources on GaAs substrates.


Source:IOPscience


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2019年4月30日星期二

Interruption-assisted epitaxy of faceted p-InAs on buffered GaSb for terahertz emitters

We demonstrate molecular beam epitaxy growth of p-InAs layers on GaAs-buffered GaSb that may be suitable for terahertz applications. GaAs buffer deposition is initiated by applying growth interruption. Reflection high-energy electron diffraction shows that GaAs growth proceeds to a quasi-two-dimensional growth mode. The scheme allows growth of a p-InAs layer 600 nm to 1.0 µm thick. Growth performed without GaAs and growth interruption resulted in decomposition of the p-InAs. When the scheme is used, the ensuing p-InAs first follows quasi-two-dimensional growth before favoring faceted islanding. Under 800-nm-wavelength femtosecond laser excitation, the p-InAs layer generates terahertz signals 70% of that of bulk p-InAs.


Source:IOPscience

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2019年4月24日星期三

Bottom-up fabrication of InAs-on-nothing MOSFET using selective area molecular beam epitaxy

In this paper we report on the fabrication and electrical characterization of InAs-on-nothing metal-oxide-semiconductor field-effect transistor composed of a suspended InAs channel and raised InAs n+ contacts. This architecture is obtained using 3D selective and localized molecular beam epitaxy on a lattice mismatched InP substrate. The suspended InAs channel and InAs n+ contacts feature a reproducible and uniform shape with well-defined 3D sidewalls. Devices with 1 μm gate length present a saturation drain current (I Dsat) of 300 mA mm−1 at V DS = 0.8 V and a trans-conductance (GM ) of 120 mS mm−1 at V DS = 0.5 V. In terms of electrostatic control, the devices display a minimal subthreshold swing of 110 mV dec−1 at V DS = 0.5 V and a small drain induced barrier lowering of 50 mV V−1.


Source:IOPscience

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2019年4月18日星期四

Comparison of InAs quantum dots grown on GaInAsP and InP

We report on the growth of InAs quantum dots (QDs) on GaInAsP and InP buffers by metal–organic chemical vapour deposition on InP(100) substrates. Indium segregation and the As–P exchange reaction affect the QD nucleation and composition. The As–P exchange reaction has a more pronounced effect on the QDs grown on the InP buffer than on those grown on the GaInAsP buffer. A very thin (0.6 nm) GaAs interlayer grown between the buffer layer and the InAs QD layer consumes segregated indium and minimizes the As/P exchange reaction. Wavelength tuning from 1450 to 1750 nm covering the technologically important 1550 nm wavelength is also achieved for the InAs QDs grown with the thin GaAs interlayer.


Source:IOPscience

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2019年4月9日星期二

Proper In deposition amount for on-demand epitaxy of InAs/GaAs single quantum dots

The test-QD in-situ annealing method could surmount the critical nucleation condition of InAs single quantum dots or GaAs single quantum dots (SQDs) to raise the growth repeatability. Here, through many growth tests on rotating substrates, we develop a proper In deposition amount (θ) for SQD growth, according to the measured critical θ for test QD nucleation (θ c). The proper ratio θ/θ c, with a large tolerance of the variation of the real substrate temperature (T sub), is 0.964−0.971 at the edge and > 0.989 but < 0.996 in the center of a 1/4-piece semi-insulating wafer, and around 0.9709 but < 0.9714 in the center of a 1/4-piece N+ wafer as shown in the evolution of QD size and density as θ/θ c varies. Bright SQDs with spectral lines at 905 nm–935 nm nucleate at the edge and correlate with individual 7 nm–8 nm-height QDs in atomic force microscopy, among dense 1 nm–5 nm-height small QDs with a strong spectral profile around 860 nm–880 nm. The higher T sub in the center forms diluter, taller and uniform QDs, and very dilute SQDs for a proper θ/θ c: only one 7-nm-height SQD in 25 μm2. On a 2-inch (1 inch = 2.54 cm) semi-insulating wafer, by using θ/θ c = 0.961, SQDs nucleate in a circle in 22% of the whole area. More SQDs will form in the broad high-T sub region in the center by using a proper θ/θ c.


Source:IOPscience

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2019年4月3日星期三

First-principles density functional theory study of strained wurtzite InP and InAs

We report on semilocal and hybrid density functional theory study of strained wurtzite crystals of InAs and InP. The crystal-field splitting has a large and nonlinear dependence on strain for both crystals. Moreover, the study of the electronic deformation potentials reveals that the well-known quasi-cubic approximation fails to reproduce the electronic features of the non-ideal c/a ratio. This theoretical study is of crucial importance for the simulation of self-assembled InAs or InP nanowires.


Source:IOPscience

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2019年3月25日星期一

Terahertz-Time Domain Spectroscopic Measurement of Moderately-Doped Silicon Using InAs Emitter under Magnetic Field

The complex refractive index of silicon using terahertz-time domain spectroscopy (THz-TDS), with an InAs wafer under the influence of a magnetic field as emitter, has been studied. By applying a magnetic field on the InAs emitter, the detected temporal waveform broadens and the spectral weight of its Fourier spectrum shifts toward the low frequency region. Calculating the real (n) and imaginary (κ) parts of the complex refractive index of silicon, it is found that with the application of a magnetic field the plots of these quantities in the low frequency region (sub-terahertz region) are smoother than those without magnetic field. These features indicate that a significant enhancement of the signal-to-noise (S/N) ratio in the low frequency region can be obtained by applying a magnetic field on the InAs emitter.



Source:IOPscience

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2019年3月18日星期一

Electrical conduction of C-implanted InAs single crystal

Carbon-ion-implanted InAs was investigated using double-crystal x-ray diffraction (DCXRD), Hall measurement and infrared absorption (IR) analysis. Multiple implantation were made at 0.1–0.4 MeV with 6.0 × 1012–2.0 × 1013 ions cm−2. After rapid thermal annealing at 300 °C for 20 s, the implantation-induced damage was removed substantially, indicating the recovery of crystallinity. The results of Hall measurement reveal strong electrical compensation and low conductivity in the implanted layer of the sample, suggesting the formation of acceptor CAs. In contrast, the lowest IR transmittance is observed in the 300 °C annealed sample, implying the existence of acceptor with significant concentration. The implanted layer turned to n-type after annealing at 400 °C with the increasing transmittance. After annealing at temperature of 500 °C, the decreasing carrier concentration and the increasing transmittance is attributed to the competition between the decomposition of C–H complexes and the formation of donor centers C–C.



Source:IOPscience

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2019年3月12日星期二

InAs-based interband cascade lasers at 4.0 μm operating at room temperature

InAs-based interband cascade lasers (ICLs) with InAs plasmon waveguides or InAs/AlSb superlattice (SL) waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the lasers with SL waveguides were 37 A/cm2 at 77 K in continuous wave mode. The operation temperature of these lasers reached room temperature in pulsed mode. Compared with the thick InAs n++ plasmon cladding layer, the InAs/AlSb superlattice cladding layers have greater advantages for ICLs with wavelengths less than 4 μm even in InAs based ICLs because in the short-wavelength region they have a higher confinement factor than InAs plasmon waveguides.



Source:IOPscience

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2019年3月5日星期二

Fabrication of thin body InAs-on-insulator structures by Smart Cut method with H+ implantation at room temperature

This paper demonstrates the fabrication of InAs-on-insulator (InAs-OI) structures with high crystallinity using the Smart Cut process, which combinates direct wafer bonding with a wafer splitting process by implanted H+. Controlling the implantation dose and rate allows us to produce wafer-level InAs-OI structures on Si substrates by H+ implantation at room temperature, which can be performed in standard implantation equipment. It is found that (111) InAs-OI has a much flatter surface after splitting than (100) one. After thinning by using CMP and wet etching, 15 nm thick InAs-OI structures are realized with the high thickness uniformity.



Source:IOPscience

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