Geometry and Thermal Stress Analysis of In-plane Outgassing Channels in Al2O3-Intermediated InP (Die)-to-Si (Wafer) Bonding

Thermal-mechanical characteristics and outgassing efficiency of integrated in-plane outgassing channels (IPOCs) at Al2O3-intermediated InP (die)-to-Si (wafer) bonding interface is investigated. The IPOCs are introduced and investigated via both multi-physics simulation and experimental demonstration. Thermal stress simulation indicates that Al2O3 bonding layer efficiently mitigates the stress as observed at top InP surface, compared to that of conventional SiO2 intermediate layer. By introducing IPOCs, the thermal stress decreases with increasing IPOC spacing-to-width (S/W) ratio. Experimentally, high quality InP/Al2O3/Si direct bonding is firstly demonstrated. Seamless bonding interface is observed, along with reasonable bond shear strength of 2.57 MPa and minimal residual stress in the transferred InP layer. Efficiency of the IPOCs is then evaluated by comparing interfacial void densities of InP bonded on dimension-varied-IPOC-patterned Si. A significant void density reduction up to two orders of magnitude is observed, with a decreasing S/W ratio. An optimal S/Wratio of 2.5 is therefore proposed to compromise between the thermal stress degradation (~10%) and outgassing efficiency improvement (~90% void density suppression). This work is thus significant as it could provide guidelines to establish high quality hybrid-integrated optoelectronic devices for Si photonic applications.

Source:IOPscience

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Low temperature InP layer transfer onto Si by helium implantation and direct wafer bonding

Helium implantation-induced layer splitting of InP in combination with direct wafer bonding was utilized to achieve low temperature layer transfer of InP onto Si(1 0 0) substrates. InP(1 0 0) wafers with 4 inch diameter were implanted by 100 keV helium ions with a dose of 5 × 1016 cm−2. Then the as-implanted wafers were coated with a spin-on glass (SOG) oxide having a thickness of 150 nm. The SOG coated InP wafers were subsequently bonded to thermally oxidized Si(1 0 0) handle wafers and the bonded wafer pairs were annealed at 200 °C for 20 h to achieve InP layer transfer onto Si(1 0 0) wafers, enabling monolithic integration of InP with Si. Cross-sectional transmission electron microscope images of the transferred InP layers revealed that the layers were about 650 nm thick, which consisted of a heavily damaged InP layer about 300 nm thick directly at the surface and a remaining 350 nm thick layer with considerably less damage.

Source:IOPscience

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Wafer Stage Staining Technique for Detection of Zn Out‐Diffusion in InGaAsP / InP Lasers

We have developed a novel staining technique to detect Zn out‐diffusion from the cladding layer into the semi‐insulating region in  laser structures. In this staining technique an Au (400Å thick) coating was applied to wafer and an aqueous  solution was used to stain the Au‐coated wafer. This technique can clearly resolve the Zn out‐diffusion profile in laser structures, and it cannot be achieved by the conventional  staining process. This is the only available technique one can use to detect zinc out‐diffusion from the p‐cladding layer into semi‐insulating  at the wafer stage and prior to device fabrication. Characterization of zinc diffusion by our technique can provide crystal growers with a timely feedback to further optimize the growth parameters.

Source:IOPscience

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Bonding temperature dependence of GaInAsP/InP laser diode grown on hydrophilically directly bonded InP/Si substrate

The bonding-temperature-dependent lasing characteristics of 1.5 a µm GaInAsP laser diode (LD) grown on a directly bonded InP/Si substrate were successfully obtained. We have fabricated the InP/Si substrate using a direct hydrophilic wafer bonding technique at bonding temperatures of 350, 400, and 450 °C, and deposited GaInAsP/InP double heterostructure layers on this InP/Si substrate. The surface conditions, X-ray diffraction (XRD) analysis, photoluminescence (PL) spectra, and electrical characteristics after the growth were compared at these bonding temperatures. No significant differences were confirmed in X-ray diffraction analysis and PL spectra at these bonding temperatures. We realized the room-temperature lasing of the GaInAsP LD on the InP/Si substrate bonded at 350 and 400 °C. The threshold current densities were 4.65 kA/cm2 at 350 °C and 4.38 kA/cm2 at 400 °C. The electrical resistance was found to increase with annealing temperature.

Source:IOPscience

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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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Photoluminescence assessment of undoped semi-insulating InP wafers obtained by annealing in iron phosphide vapour

We have investigated the photoluminescence mapping characteristics of semi-insulating (SI) InP wafers obtained by annealing in iron phosphide ambience (FeP2-annealed). Compared with as-grown Fe-doped and undoped SI InP wafers prepared by annealing in pure phosphorus vapour (P-annealed), the FeP2-annealed SI InP wafer has been found to exhibit a better photoluminescence uniformity. Radial Hall measurements also show that there is a better resistivity uniformity on the FeP2-annealed SI InP wafer. When comparing the distribution of deep levels between the annealed wafers measured by optical transient current spectroscopy, we find that the incorporation of iron atoms into the SI InP suppresses the formation of a few defects. The correlation observed in this study implies that annealing in iron phosphorus ambience makes Fe atoms diffuse uniformly and occupy the indium site in the SI InP lattice. As it stands, we believe that annealing undoped conductive InP in iron phosphide vapour is an effective means to obtain semi-insulating InP wafers with superior uniformity.

Source:IOPscience

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Crystalline Defects in InP-to-Silicon Direct Wafer Bonding

InP-to-Si wafer bonding has been proposed as a way of circumventing the problems associated with lattice-mismatch in heteroepitaxial growth. Therefore, in this study the dislocation density and material degradation in InP-to-Si hydrophobic bonding are evaluated. Both interface and InP bulk defects were studied using IR-transmission, atomic force microscopy (AFM) and defect-etching. When the bonded wafers were annealed below 300°C, no volume dislocations were generated in InP. However, when annealing above 300°C, the thermal mismatch stress induced large numbers of volume dislocations in InP. It was also shown that hydrophobic InP-to-Si wafer bonding unfortunately requires high-temperature annealing to achieve sufficient bonding-strength. However, a considerably lower dislocation density was observed in InP-to-Si wafer bonding than that in InP heteroepitaxial growth on Si. Also, when the samples were annealed above 400°C, asymmetric voids emerged at the interface. These voids are associated with the nucleation of indium droplets which causes microcavities at the interface where volume dislocations can sweep-out, forming surface steps. The voids completely disappeared when channel-patterned interfaces were used.

Source:IOPscience

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Room-temperature GaAs/InP wafer bonding with extremely low resistance

Low-temperature direct wafer bonding is a promising technique for fabricating multijunction solar cells with more than four junctions in order to obtain high conversion efficiencies. However, it has been difficult to reduce the bond interface resistance between a GaAs-based subcell wafer and an InP-based subcell wafer. We found that a novel bonding structure comprising heavily Zn-doped (1 ×1019 cm−3) p+-GaAs and S-doped (3 × 1018 cm−3) n-InP had an interface resistance of 2.5 × 10−5 Ωcm2, which is the lowest value ever reported. This result suggests that the newly developed room-temperature wafer bonding technique has high potential to realize high-efficiency multijunction solar cells.

Source:IOPscience

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Wafer-scale self-organized InP nanopillars with controlled orientation for photovoltaic devices

A unique wafer-scale self-organization process for generation of InP nanopillars is demonstrated, which is based on maskless ion-beam etching (IBE) of InP developed to obtain the nanopillars, where the height, shape, and orientation of the nanopillars can be varied by controlling the processing parameters. The fabricated InP nanopillars exhibit broadband suppression of the reflectance, 'black InP,' a property useful for solar cells. The realization of a conformal p–n junction for carrier collection, in the fabricated solar cells, is achieved by a metalorganic vapor phase epitaxy (MOVPE) overgrowth step on the fabricated pillars. The conformal overgrowth retains the broadband anti-reflection property of the InP nanopillars, indicating the feasibility of this technology for solar cells. Surface passivation of the formed InP nanopillars using sulfur-oleylamine solution resulted in improved solar-cell characteristics. An open-circuit voltage of 0.71 V and an increase of 0.13 V compared to the unpassivated device were achieved.



Source:IOPscience

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Local electronic transport through InAs/InP(0 0 1) quantum dots capped with a thin InP layer studied by an AFM conductive probe

An AFM combined with a SEM has been used to study the topography and the local electronic transport through InAs QDs grown by metalorganic vapour phase epitaxy (MOVPE) on an n-type InP(0 0 1) substrate and covered by a 5 nm thick InP cap-layer. Images reveal that elliptic terrace-like structures have been formed around the QDs and that the height of the QDs has been decreased to that of the cap-layer. The electric current is very high on the dots, about ten times less on the terraces, and not detectable on the wetting layer. Mechanisms of electronic transport through the sample are discussed, based on current–voltage characteristics and energy band diagrams. The detection of the electron beam induced current (EBIC) with the conductive probe shows that the minority carrier diffusion length, the holes in our case, is about two times larger than that of the reference sample containing no QDs. Mechanisms of charge trapping inside the QDs and the surrounding terraces in forward bias conditions are also discussed. A temporary memory effect is evidenced.

Source:IOPscience

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An experimental investigation of Zn diffusion into InP and InGaAs

In this report, we investigate the profiles of zinc (Zn) in n-type InP 100 single crystal wafers and InGaAs epitaxial film prepared by semi-closed ampoule Zn diffusion. The different annealing effect on junction depth and concentration for InP and InGaAs is studied, and the difference is tentatively ascribed to solubility for each material. The maximum net acceptor concentration in InP changes from 3.3 × 1017 cm−3 to 3.3 × 1018 cm−3 before and after annealing, and the later value is close to the solubility limit for closed-ampoule Zn diffusion InP. Annealing does not make the maximum net acceptor concentration and depth in InGaAs change much. Our experiments show that Zn diffusion InGaAs can be used as a good ohmic contact material for photoelectric devices due to its high acceptor concentration.

Source:IOPscience

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Improved InAsP metamorphic layers grown on an InP substrate using underlying InP grown at low temperatures

The use of an InP epitaxial layer grown at low temperatures before the growth of a step-graded InAsP metamorphic buffer has been shown to provide a large improvement in the crystal quality of the final metamorphic layer. The improvement is evidenced by over an order of magnitude increase in photoluminescence intensity as well as a large reduction of the mosaic spread and the overall tilt of the relaxed layers



Source:IOPscience

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Transport properties of metal–semiconductor junctions on n-type InP prepared by electrophoretic deposition of Pt nanoparticles

Electrical properties of highly rectifying Pt/InP junctions fabricated by electrophoretic deposition of Pt nanoparticles are investigated at different temperatures by the measurement of current–voltage and capacitance–voltage characteristics. The forward I–V characteristics of the junction are described by thermionic emissions theory at low forward bias (3kT/q < V < 0.2 V) and by tunnelling current transport through the narrowed space charge region at forward bias V > 0.2 V. The reverse I–V characteristics are analysed in the scope of the thermionic emission model in the presence of shunt resistance. Electrical characteristics of these diodes are sensitive to gas mixtures with a low hydrogen concentration and show an extremely fast response and recovery time.

Source:IOPscience

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Room-Temperature Annealing Effects on Radiation-Induced Defects in InP Crystals and Solar Cells

Remarkable defect annealing in both p-type and n-type InP following 1-MeV electron irradiation has been observed at room temperature, resulting in the recovery of InP solar cell properties. The room-temperature annealing characteristics of radiation-induced defects in InP were studied by measuring InP solar cell photovoltaic properties in conjunction with deep-level transient spectroscopy. The recovery of InP solar cell radiation damage is found to be due mainly to the room-temperature annihilation of radiation-induced recombination centers such as an H4 trap (Ev+0.37 eV) in p-InP. Moreover, the room-temperature annealing rate of radiation-induced defects in InP was found to be proportional to the 2/3 power of the carrier concentration. Additionally, a model has been considered in which point defects diffuse to sinks through impurities so as to annihilate and bind with impurities, thus forming point defect-impurity complexes.

Source:IOPscience

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Efficient ion-slicing of InP thin film for Si-based hetero-integration

Integration of high quality single crystalline InP thin film on Si substrate has potential applications in Si-based photonics and high-speed electronics. In this work, the exfoliation of a 634 nm crystalline InP layer from the bulk substrate was achieved by sequential implantation of He ions and H ions at room temperature. It was found that the sequence of He and H ion implantations has a decisive influence on the InP surface blistering and exfoliation, which only occur in the InP pre-implanted with He ions. The exfoliation efficiency first increases and then decreases as a function of H ion implantation fluence. A kinetics analysis of the thermally activated blistering process suggests that the sequential implantation of He and H ions can reduce the InP thin film splitting thermal budget dramatically. Finally, a high quality 2 inch InP-on-Si(100) hetero-integration wafer was fabricated by He and H ion sequential implantation at room temperature in combination with direct wafer bonding.

Source:IOPscience

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Simulation for silicon-compatible InGaAs-based junctionless field-effect transistor using InP buffer layer

In this paper, we present the optimized performances of indium gallium arsenide (InGaAs)-based compound junctionless field-effect transistors (JLFETs) using an indium phosphide (InP) buffer layer. The proposed InGaAs-InP material combination with little lattice mismatch provides a significant improvement in current drivability securing various potential applications. Device optimization is performed in terms of primary dc parameters and characterization is investigated by two-dimensional (2D) technology computer-aided design simulations. The optimization variables were the channel doping concentration (Nch), the buffer doping concentration (Nbf), and the channel thickness (Tch). For the optimally designed InGaAs JLFET, on-state current (Ion) of 325 µA µm−1, subthreshold swing (S) of 80 mV dec−1, and current ratio (Ion/Ioff) of 109 were obtained. In the end, the results are compared with the data of silicon (Si)-based JL MOSFETs to confirm the improvements.

Source:IOPscience

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Incorporation of Arsenic and Gallium in InP Layers in GaInAs/InP Heterostructures Grown by MOVPE

The effects of arsenic (As) and gallium (Ga) incorporation in InP layers in GaInAs/InP heterostructures grown by low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) on lattice parameter and band-gap energy of InP layers were studied. It was found that As and Ga incorporation is prolonged during InP growth after arsine (AsH3) and triethylgallium (TEG) flows are turned off, resulting in a lowering of the band gap energy and change in the lattice parameter of the InP layers. This incorporation is considered to originate from both desorption and diffusion of their outgassing sources produced during the growth of a thick GaInAs layer.

Source:IOPscience

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The influence of argon pressure and RF power on the growth of InP thin films

Indium phosphide thin films were grown onto glass substrates by RF magnetron sputtering. In this paper, we present a study on the role of argon pressure and rf power on magnetron sputtered InP films. These sputtering parameters are shown to affect the deposition rate, structure, morphology, electrical and optical properties of InP films. Single-phase, nearly stoichiometric and polycrystalline films exhibiting zinc blende structure with strong preferred orientation along (1 1 1) were observed at an argon pressure of 0.4 Pa, by keeping the substrate temperature (448 K) and RF power (150 W) constant. Hall measurements indicated n-type conductivity in InP films. The optical absorption studies indicated a direct band gap of 1.35 eV.

Source:IOPscience

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Towards a monolithically integrated III–V laser on silicon: optimization of multi-quantum well growth on InP on Si

High-quality InGaAsP/InP multi-quantum wells (MQWs) on the isolated areas of indium phosphide on silicon necessary for realizing a monolithically integrated silicon laser is achieved. Indium phosphide layer on silicon, the pre-requisite for the growth of quantum wells is achieved via nano-epitaxial lateral overgrowth (NELOG) technique from a defective seed indium phosphide layer on silicon. This technique makes use of epitaxial lateral overgrowth (ELOG) from closely spaced (1 µm) e-beam lithography-patterned nano-sized openings (~300 nm) by low-pressure hydride vapor phase epitaxy. A silicon dioxide mask with carefully designed opening patterns and thickness with respect to the opening width is used to block the defects propagating from the indium phosphide seed layer by the so-called necking effect. Growth conditions are optimized to obtain smooth surface morphology even after coalescence of laterally grown indium phosphide from adjacent openings. Surface morphology and optical properties of the NELOG indium phosphide layer are studied using atomic force microscopy, cathodoluminescence and room temperature µ-photoluminescence (µ-PL) measurements. Metal organic vapor phase epitaxial growth of InGaAsP/InP MQWs on the NELOG indium phosphide is conducted. The mask patterns to avoid loading effect that can cause excessive well/barrier thickness and composition change with respect to the targeted values is optimized. Cross-sectional transmission electron microscope studies show that the coalesced NELOG InP on Si is defect-free. PL measurement results indicate the good material quality of the grown MQWs. Microdisk (MD) cavities are fabricated from the MQWs on ELOG layer. PL spectra reveal the existence of resonant modes arising out of these MD cavities. A mode solver using finite difference method indicates the pertinent steps that should be adopted to realize lasing.

Source:IOPscience

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Epitaxial CdS Layers Deposited on InP Substrates

The CdS layers were deposited on InP substrates by using the (H2–CdS) vapor growth technique. The single crystal layers of hexagonal CdS were obtained on InP (111), (110) and (100) with the following heteroepitaxial relationships; (0001) CdS//(111) InP and [bar 12bar 10] CdS//[01bar 1] InP, (01bar 13) CdS//(110) InP and [bar 2110] CdS//[bar 110] InP, (30bar 34) CdS//(100) InP and [bar 12bar 10] CdS//[01bar 1] InP. The CdS layers deposited on InP (bar 1bar 1bar 1) were identfied in terms of the twinned hexagonal crystals, twin planes of which were nearly parallel to (30bar 3bar 4) and its crystallographic equivalents. The compositional gradients were observed at the interface of the deposits and the substrates.

Source:IOPscience

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Evaluation of semi-insulating Ti-doped and Mn-doped InP for radiation detection

Semi-insulating and semiconducting InP single crystals without intentional doping and doped with Fe, co-doped with Zn and Ti and doped with Mn were grown using the Czochralski technique. Hall effect measurements and deep level transient spectroscopy were used to characterize samples cut from these crystals. Two electron traps were found in undoped InP whose concentration was suppressed in Mn-doped InP. Binding energies of Fe, Ti and Mn deep level impurities were determined from the temperature-dependent Hall effect measurements. The curves of Hall coefficient versus reciprocal temperature decline from straight lines at low temperatures for InP:Fe and for InP:Ti samples due to electron and hole mixed conductance. The resistivity of InP:Ti is equal to about 106 Ωm at the lowered temperature of 230 K. This value of resistivity and the small hole capture rate of Ti makes this material suitable for radiation detection at the lowered temperature.

Source:IOPscience

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MOCVD Growth of InP on 4-inch Si Substrate with GaAs Intermediate Layer

This letter describes the heteroepitaxy of InP on Si by MOCVD. A new epitaxial structure with a thin GaAs intermediate layer (InP/GaAs/Si) is proposed to alleviate the large lattice mismatch (8.4%) between InP and Si. Using this structure, a 4-inch InP single crystal with a mirror-like surface and good thickness uniformity (Δd/d=±10%) was obtained. Residual stress in the InP film was 5.7±108 dyn/ cm2 for the InP/GaAs/Si structure, as compared to 8.3×108 dyn/cm2 for the InP directly grown on Si. This shows that the GaAs intermediate layer is also effective in reducing the residual stress in the InP epilayer.

Source:IOPscience

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Optical properties of Zn-diffused InP layers for the planar-type InGaAs/InP photodetectors

Zn diffusion into InP was carried out ex-situ using a new Zn diffusion technique with zinc phosphorus particles placed around InP materials as zinc source in a semi-closed chamber formed by a modified diffusion furnace. The optical characteristics of the Zn-diffused InP layer for the planar-type InGaAs/InP PIN photodetectors grown by molecular beam epitaxy (MBE) has been investigated by photoluminescence (PL) measurements. The temperature-dependent PL spectrum of Zn-diffused InP samples at different diffusion temperatures showed that band-to-acceptor transition dominates the PL emission, which indicates that Zn was commendably diffused into InP layer as the acceptor. High quality Zn-diffused InP layer with typically smooth surface was obtained at 580 °C for 10 min. Furthermore, more interstitial Zn atoms were activated to act as acceptors after a rapid annealing process. Based on the above Zn-diffusion technique, a 50 μm planar-type InGaAs/InP PIN photodector device was fabricated and exhibited a low dark current of 7.73 pA under a reverse bias potential of −5 V and a high breakdown voltage of larger than 41 V (I < 10 μA). In addition, a high responsivity of 0.81 A/W at 1.31 μm and 0.97 A/W at 1.55 μm was obtained in the developed PIN photodetector.

Source:IOPscience

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Weakly doped InP layers prepared by liquid phase epitaxy using a modulated cooling rate

Epitaxial structures based on InP are widely used to manufacture a number of devices such as microwave transistors, light-emitting diodes, lasers and Gunn diodes. However, their temporary instability caused by heterogeneity of resistivity along the layer thickness and the influence of various external or internal factors prompts the need for the development of a new reliable technology for their preparation. Weak doping by Yb, Al and Sn together with modulation of the cooling rate applied to prepare InP epitaxial layers is suggested to be adopted within the liquid phase epitaxy (LPE) method. The experimental results confirm the optimized conditions created to get a uniform electron concentration in the active n-InP layer. A sharp profile of electron concentration in the n+-InP(substrate)/n-InP/n+-InP epitaxial structure was observed experimentally at the proposed modulated cooling rate of 0.3 °С–1.5 °С min−1. The proposed technological method can be used to control the electrical and physical properties of InP epitaxial layers to be used in Gunn diodes.

Source:IOPscience

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Growth of InP directly on Si by corrugated epitaxial lateral overgrowth

In an attempt to achieve an InP–Si heterointerface, a new and generic method, the corrugated epitaxial lateral overgrowth (CELOG) technique in a hydride vapor phase epitaxy reactor, was studied. An InP seed layer on Si (0 0 1) was patterned into closely spaced etched mesa stripes, revealing the Si surface in between them. The surface with the mesa stripes resembles a corrugated surface. The top and sidewalls of the mesa stripes were then covered by a SiO2 mask after which the line openings on top of the mesa stripes were patterned. Growth of InP was performed on this corrugated surface. It is shown that growth of InP emerges selectively from the openings and not on the exposed silicon surface, but gradually spreads laterally to create a direct interface with the silicon, hence the name CELOG. We study the growth behavior using growth parameters. The lateral growth is bounded by high index boundary planes of {3 3 1} and {2 1 1}. The atomic arrangement of these planes, crystallographic orientation dependent dopant incorporation and gas phase supersaturation are shown to affect the extent of lateral growth. A lateral to vertical growth rate ratio as large as 3.6 is achieved. X-ray diffraction studies confirm substantial crystalline quality improvement of the CELOG InP compared to the InP seed layer. Transmission electron microscopy studies reveal the formation of a direct InP–Si heterointerface by CELOG without threading dislocations. While CELOG is shown to avoid dislocations that could arise due to the large lattice mismatch (8%) between InP and Si, staking faults could be seen in the layer. These are probably created by the surface roughness of the Si surface or SiO2 mask which in turn would have been a consequence of the initial process treatments. The direct InP–Si heterointerface can find applications in high efficiency and cost-effective Si based III–V semiconductor multijunction solar cells and optoelectronics integration.

Source:IOPscience

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Fe Doping and Preparation of Semi-Insulating InP by Wafer Annealing under Fe Phosphide Vapor Pressure

Semi-insulating (SI) InP has been industrially produced by doping Fe atoms as deep acceptors. Fe concentrations in InP are, however, largely varied from top to tail along the crystal growth axis due to impurity segregation. In the present work, we have examined the possibility of vapor-phase Fe doping for fabrication of 50- and 75-mm-diameter SI InP wafers with constant Fe concentrations using a wafer annealing procedure. A small amount of Fe was charged with red phosphorus in ampoules in which InP wafers were annealed. It was found that the vapor-phase doping is effective for Fe doping of InP. The present technology can be applied for the fabrication of low Fe-doped SI InP wafers with similar Fe concentrations of all wafers from one InP ingot.

Source:IOPscience

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Modelling dislocation generation in high pressure Czochralski growth of InP single crystals: part II

The visco-plastic model developed in part I of this work is used here to study the dislocation evolution in high pressure Czochralski growth of InP single crystals. Towards this an in-house computational fluid dynamics code MASTRAPP is linked to the ABAQUS software. MASTRAPP has the capability to predict the thermal field history in the Czochralski furnace throughout the growth period. The thermal loading history determined through MASTRAPP is fed to ABAQUS and the visco-plastic constitutive equations are integrated while maintaining force equilibrium in the growing crystal. The combined model predicts the final dislocation densities in the crystal at the end of the growth period. It is then used to study and predict the effect of various parameters and phenomena on the final dislocation densities—thermal shock, gas convection, height of boric oxide encapsulant layer, marginal roles of thermal radiation and melt convection, and the cool down period. Gas convection is found to have the most significant effect on the dislocation densities.

Source:IOPscience

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