Indium Phosphide Single Crystals Research Articles

Large-area single-crystal indium phosphide laterally grown on patterned silicon-on-insulator

Large-area single-crystal indium phosphide laterally grown on patterned silicon-on-insulator

Indium Phosphide Single Crystal Furnace Cooling Crystallization Temperature Control Model Research.

Indium phosphide (InP) single crystals, as key III-V compound semiconductor materials, play an irreplaceable role in various fields, such as optical communication and microwave millimeter-wave communication. Vertical gradient freeze (VGF) has become one of the main methods for industrial production of InP single crystals due to its advantages in temperature gradient control. However, defects such as twins and dislocations are easily generated during the production of InP single crystals by the VGF method. Through an in-depth study of the thermal field during the growth of InP single crystals, it is found that the cooling rate of the thermal field during single crystal growth is crucial and is closely related to the generation of twins, dislocations, and polycrystallization defects. Therefore, constructing a cooling model based on temperature control and the quality of InP single crystals has a positive driving effect on improving the yield of single crystal products. In this paper, by establishing a thermal field model of an InP single crystal furnace produced by the VGF method, the characteristics of temperature variation are analyzed in depth. Subsequently, numerical analysis of discrete cooling data during the cooling crystallization process is conducted, considering the quality of the InP single crystal growth. Combined with the spline regression algorithm, the optimal cooling model is fitted. Through positive and reverse experiment verification, the model shows significant effects in controlling internal stress in the crystal and reducing defect generation. Based on this model, we have successfully achieved effective suppression of defects, such as twins and dislocations, thereby significantly improving the quality of InP single crystals. This research not only provides a solid theoretical basis for the production of InP single crystals but also provides strong support for experimental applications.

High-throughput and cost-effective method for production of high-quality semi-insulating InP substrates

A novel technique for preparation of high-resistivity indium phosphide (InP) via post-growth treatment of undoped n-type wafers is presented. The method includes the deposition of a controlled quantity of iron on both faces of as-cut wafers by a simple chemical bath, and the subsequent Fe diffusion by thermal annealing. The reproducible low - to – high resistivity conversion is explained considering two simultaneous phenomena: the annealing-controlled in-diffusion of Fe deep acceptors and the out-diffusion of hydrogen-related shallow donors. Differently from standard Fe-doped melt-grown InP single crystals, this process does not suffer from segregation, thus the Fe-concentration is constant from wafer to wafer, with no striations and radial gradients deriving from the convex solid–liquid interface during growth. Main advantages of the developed process are: i) an entire undoped InP boule may be sliced and converted to semi-insulating, which makes the process cost-effective; ii) reproducible and uniform semi-insulating properties from batch to batch of wafers; iii) the Fe incorporation is precisely controlled, and minimized, so that electrical characteristics of Fe-diffused wafers are superior to those of traditional semi-insulating melt-grown InP crystals doped via addition of elemental Fe to the melt.

Functional model for the synthesis of nanostructures of the given quality level

Purpose: The aim of this paper is to develop a functional model for the synthesis of nanostructures of the given quality level, which will allow to effectively control the process of nanopatterning on the surface of semiconductors with tunable properties. Design/methodology/approach: The paper uses the IDEF0 methodology, which focuses on the functional design of the system under study and describes all the necessary processes with an accuracy sufficient for an unambiguous modelling of the system's activity. Based on this methodology, we have developed a functional model for the synthesis of nanostructures of the given quality level and tested its effectiveness through practice. Findings: The paper introduces a functional model for the synthesis of nanostructures on the surface of the given quality level semiconductors and identifies the main factors affecting the quality of nanostructures as well as the mechanisms for controlling the formation of porous layers with tunable properties. Using the example of etching single-crystal indium phosphide electrochemically in a hydrochloric acid solution, we demonstrate that the application of the suggested model provides a means of forming nanostructures with tunable properties, assessing the quality level of the nanostructures obtained and bringing the parameters in line with the reference indicators at a qualitatively new level. Research limitations/implications: Functional modelling using the IDEF0 methodology is widely used when process control is required. In this study it has been applied to control the synthesis of nanostructures of the given quality level on the surface of semiconductors. However, these studies require continuation, namely, the establishment of correlations between the technological and resource factors of synthesis and the acquired properties of nanostructures. Practical implications: This study has a significant practical effect. Firstly, it shows that functional modelling can reduce the time required to form large batches of the given quality level nanostructures. This has made it possible to substantiate the choice of the initial semiconductor parameters and nanostructure synthesis modes in industrial production from the theoretical and empirical perspective. Secondly, the presented methodology can be applied to control the synthesis of other nanostructures with desired properties and to reduce the expenses required when resources are depleted and the cost of raw materials is high. Originality/value: This paper is the first to apply the IDEF0 methodology to control the given quality nanostructure synthesis. This paper will be of value to engineers who are engaged in the synthesis of nanostructures, to researchers and scientists as well as to students studying nanotechnology.

Influence of melt convection on distribution of indium inclusions in liquid-encapsulated Czochralski-grown indium phosphide crystals

Indium (In) inclusions have been found in 〈100〉 indium phosphide (InP) single crystals grown in In-rich melt by the liquid-encapsulated Czochralski (LEC) method. Two kinds of In inclusions with different morphologies, one is lath-like and the other is polyhedral, have been observed. Most of the In inclusions are lath-like and their long sides are always parallel to the $$[0\overline{1}1]$$ or $$[0{\overline{1}}{\overline{1}}]$$ orientation. In (100) InP wafers, these inclusions mainly distribute in two regions viz., center of the wafer and annular belt at a certain distance from the center. These special distributions of In inclusions in InP crystals were found in our experiments for the first time. In order to clarify the cause of the special distributions of In inclusions, numerical simulations have been carried out on the melt convection in the process of InP crystal growth. The results show that the rotations of crystal and crucible significantly affect the number and direction of convection cells in the melt, which have a great influence on the enrichment and distribution of excess In at the solid–liquid interface. Different melt convections modify the radial distributions of excess In atoms near the solid–liquid interface and result in different radial distributions of In inclusions in the crystals.

Engineering Complex Synaptic Behaviors in a Single Device: Emulating Consolidation of Short-term Memory to Long-term Memory in Artificial Synapses via Dielectric Band Engineering.

As one of the key neuronal activities associated with memory in the human brain, memory consolidation is the process of the transition of short-term memory (STM) to long-term memory (LTM), which transforms an external stimulus to permanently stored information. Here, we report the emulation of this complex synaptic function, consolidation of STM to LTM, in a single-crystal indium phosphide (InP) field effect transistor (FET)-based artificial synapse. This behavior is achieved via the dielectric band and charge trap lifetime engineering in a dielectric gate heterostructure of aluminum oxide and titanium oxide. We analyze the behavior of these complex synaptic functions by engineering a variety of action potential parameters, and the devices exhibit good endurance, long retention time (>105 s), and high uniformity. Uniquely, this approach utilizes growth and device fabrication techniques which are scalable and back-end CMOS compatible, making this InP synaptic device a potential building block for neuromorphic computing.

Homoepitaxial Growth of InP on Electrochemical Etched Porous InP Surface

Single crystal indium phosphide (InP) layers were epitaxially grown on porous (001) InP surfaces with controlled porosities. Changes in the underlying porous layer structure, and hence its stability, during epitaxial growth at elevated temperatures were observed. The same change in the porous structure was achieved by only annealing under the same growth conditions. A 100%-layer transfer rate is demonstrated for annealed dual porous InP layers. Plan-view transmission electron microscopy (TEM) images of the epitaxial layer show that the layer is continuous over the porous underlayer and had a dislocation density lower than 3 × 106 cm−2. The high crystallinity of the epitaxy layer was verified by high resolution X-ray diffraction (HRXRD) rocking curve scans. These high quality epitaxial layers grown on porous InP show promise for active layers in thin, flexible high-performance devices, which are readily transferred from the growth substrate by fracture at the epitaxial-porous layer interface.

Amorphization of Indium Phosphide Single Crystals by Swift Heavy Ion Bombardment

Journal Article Amorphization of Indium Phosphide Single Crystals by Swift Heavy Ion Bombardment Get access AS Khalil AS Khalil Mining and Metallurgy Department, Tabbin Institute for Metallurgical Studies (TIMS), Helwan, POB 109, Cairo, Egypt Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 21, Issue S3, 1 August 2015, Pages 1011–1012, https://doi.org/10.1017/S1431927615005851 Published: 23 September 2015

Elastic constants of nanoporous III-V semiconductors

Resonant ultrasound spectroscopy is applied to determine elastic constants of nanoporous gallium arsenide and indium phosphide single crystals with various pore morphologies. Three samples with approximately the same level of porosity (30%) are studied; it is shown that in all cases this porosity leads to a decrease of Young’s moduli by more than 50% and to a significant increase of the Poisson’s ratios, while the strength of the resulting elastic anisotropy of the nanoporous material follows from the particular morphology of the pores. The experimentally obtained elastic constants are compared to those predicted for the given morphologies by finite elements modeling. It is observed that the numerical models give acceptably realistic predictions of the elastic constants, although they tend to underestimate the decrease of the elastic moduli due to the porosity as well as the corresponding increase of the Poisson’s ratio.

Growth of Polycrystalline Indium Phosphide Nanowires on Copper

ABSTRACTOur nation discards more than 50% of the total input energy as waste heat in various industrial processes such as metal refining, heat engines, and cooling. If we could harness a small fraction of the waste heat through the use of thermoelectric (TE) devices while satisfying the economic demands of cost versus performance, then TE power generation could bring substantial positive impacts to our society in the forms of reduced carbon emissions and additional energy. To increase the unit-less figure of merit, ZT, single-crystal semiconductor nanowires have been extensively studied as a building block for advanced TE devices because of their predicted large reduction in thermal conductivity and large increase in power factor. In contrast, polycrystalline bulk semiconductors also indicate their potential in improving overall efficiency of thermal-to-electric conversion despite their large number of grain boundaries. To further our goal of developing practical and economical TE devices, we designed a material platform that combines nanowires and polycrystalline semiconductors which are integrated on a metallic surface. We will assess the potential of polycrystalline group III-V compound semiconductor nanowires grown on low-cost copper sheets that have ideal electrical/thermal properties for TE devices. We chose indium phosphide (InP) from group III-V compound semiconductors because of its inherent characteristics of having low surface states density in comparison to others, which is expected to be important for polycrystalline nanowires that contain numerous grain boundaries. Using metal organic chemical vapor deposition (MOCVD) polycrystalline InP nanowires were grown in three-dimensional networks in which electrical charges and heat travel under the influence of their characteristic scattering mechanisms over a distance much longer than the mean length of the constituent nanowires. We studied the growth mechanisms of polycrystalline InP nanowires on copper surfaces by analyzing their chemical, optical, and structural properties in comparison to those of single-crystal InP nanowires formed on single-crystal surfaces. We also assessed the potential of polycrystalline InP nanowires on copper surfaces as a TE material by modeling based on finite-element analysis to obtain physical insights of three-dimensional networks made of polycrystalline InP nanowires. Our discussion will focus on the synthesis of polycrystalline InP nanowires on copper surfaces and structural properties of the nanowires analyzed by transmission electron microscopy that provides insight into possible nucleation mechanisms, growth mechanisms, and the nature of grain boundaries of the nanowires.

Microstructural and optoelectronic properties of polycrystalline InP films deposited by RF magnetron sputtering

Indium phosphide (InP) films were deposited onto glass substrates using RF magnetron sputtering by varying the substrate temperature (348–573K), under constant argon pressure (0.4Pa) and RF power (150W). Substrate temperature found to have significant influence on the composition, 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 (111), was observed for the films grown at a substrate temperature of 448K. Conical shaped grain growth was observed in the grown films. Hall measurements revealed n-type conductivity in the InP films. The optical absorption studies indicated a direct band gap of 1.35eV. Various lattice vibrational modes observed by Raman measurements were found to match well with those reported for single-crystal InP.

Surface and subsurface damages in nanoindentation tests of compound semiconductor InP

Nanoindentation tests were conducted on single-crystal indium phosphide (InP) using a Vickers indenter and a spherical indenter over a wide load range. The resulting indents were examined using scanning electron microscopy, cross-sectional transmission electron microscopy and selected area diffraction. Effects of the indenter type and indentation load on the surface cracking behavior, load–displacement characteristics and subsurface damage were investigated. The results showed that the cracking behavior and critical load for crack generation depends strongly on the indenter geometry and orientation. Pop-in events occur during loading in the case of the spherical indenter, but not in the case of the Vickers indenter. It was demonstrated that dislocations dominate the deformation mechanism, and no phase transformation occurs. The indenter contact immediately causes a high-density dislocation region, below which extend slip bands. The stress field of the indented zone was simulated by the finite element method, and the stress concentration regions corresponded to the high-density dislocation regions.

Finite element modeling of dislocation reduction in GaAs and InP single crystals grown from the VGF process

Dislocations in gallium arsenide (GaAs) and indium phosphide (InP) crystals are generated by thermal stresses induced during their solidification process of crystal growth. High dislocation density in these crystals will reduce the performance and reliability of the GaAs- and InP-based microelectronic and photonic devices/circuits. It has been known that doping impurity atoms into GaAs and InP crystals during their solidification process can significantly reduce dislocation densities generated in these crystals. A viscoplastic constitutive equation that couples a microscopic dislocation density and impurity atoms with a macroscopic plastic deformation is employed in a transient finite element model for predicting the dislocation density generated in the undoped and doped GaAs and InP crystals grown by the vertical gradient freeze (VGF) process. The effects of crystal growth parameters (i.e., imposed temperature gradient, crystal diameter, and crystal growth rate) on dislocation generation are also investigated. The numerical results show that doping impurity can significantly reduce the dislocation density generated in these crystals. It also shows that dislocation density reduces drastically as the crystal diameter and imposed temperature gradient decrease, but the crystal growth rate has almost no effect on dislocation generation in these crystals.

Dislocation reduction in sulfur- and germanium-doped indium phosphide single crystals grown by the vertical gradient freeze process: A transient finite-element study

During the growth of indium phosphide (InP) crystals, dislocations are mostly generated in a plastically deformed crystal due to crystallographic glide caused by excessive thermal stresses. High dislocation density presented in the InP crystal can reduce the performance, lifetime, and reliability of the InP-based microelectronic and optoelectronic devices/circuits. The generation of dislocations in InP single crystals grown from the melt can be predicted by using a transient finite-element model. This model couples microscopic dislocation motion and multiplication to macroscopic plastic deformation during the crystal growth process. The temperature fields in the crystal are determined by solving the partial differential equations of heat transfer for the vertical gradient freeze (VGF) process. These temperature fields are then employed to the transient finite-element model to study the effects of doping impurities and growth parameters (i.e., imposed temperature gradient, crystal radius, and growth rate) on dislocation reduction in InP crystals grown by different VGF processes.

Annealing behavior of implanted helium in indium phosphide

The thermal stability of He3 implanted into single crystal indium phosphide has been studied as a function of postimplant annealing temperature between 150 and 600 °C and annealing temperature ramp rate in the range 0.1–20 ° C/s. Retention of implanted helium (implant energy 1.0 MeV and fluence 1.0×1016 cm−2) is measured via the He3(d,p)4 nuclear reaction. Helium is shown to be a facile diffuser unless trapped by implantation induced defects. The temperature ramp rate is shown to be a dominant parameter in determining the fraction of implanted helium that becomes trapped in voids.

Implantation Induced Selective Chemical Etching of Indium Phosphide

Single-crystal indium phosphide wafer samples have been implanted through a stencil mask with single energy indium ions at 2, 5, and 8 MeV to fluences of 2, 2, and respectively. Specimens were then etched in a concentrated solution of at room temperature. Selective etching of the implanted regions resulted in transfer of the mask pattern to the InP substrate. Etch rates were determined from step height profilometry measurements across the patterned surface. A wet chemical etch rate of was observed for the ion implanted material, a rate three orders of magnitude higher than the 2 nm/min measured for unimplanted single crystal material. © 2001 The Electrochemical Society. All rights reserved.

Deformations induced by a Vickers indentor in InP at room temperature

(001) surfaces of indium phosphide (InP) single crystals have been deformed at room temperature by a Vickers indenter. The indents formed were observed by transmission electron microscopy (TEM) in plan views as well as in cross-sectional views obtained by focused-ion beam (FIB) milling. The in-depth structure of the plastic zone has been investigated as well as the dislocation arrangements. The polarity of the crystal was determined by convergent beam electron diffraction (CBED) and the plastic anisotropy was discussed.

Co-Implantation and the Role of Implant Damage in the Thermal Stability of Implanted Helium in Indium Phosphide

AbstractThe thermal stability of 3He implanted into single crystal indium phosphide has been studied. Helium diffuses in the 200°C-300°C temperature range unless stabilized by bubbles which trap helium up to the 400°C-500°C temperature range. The efficiency of bubble formation, as measured by the fraction of implanted helium retained to 400°C is increased by: 1) increasing the helium fluence, 2) increasing the temperature ramp rate, 3) co-implantation with a second ion species, or 4) implanting at elevated temperature. The mechanism by which these processes enhance bubble formation can be understood in terms of a model where the nucleation of bubbles occurs at elevated temperature in the presence of both lattice defects and helium atoms.

Compton scattering studies of the electron momentum distribution in indium phosphide

Abstract The electron momentum anisotropy of indium phosphide has been studied by measuring the directional Compton profiles of indium phosphide single crystals with the use of radiation from an 241 Am gamma source. Three different samples, cut along the [100], [110] and [111] planes, were used. The experimental anisotropy has been compared with the results based on the linear combination of Gaussian orbitals (LCGO) method. The agreement is very good with our theoretical results. It is found that the extrema appearing in the dependences on q of the anisotropies have an intimate connection with the bonding properties of the semiconductor. A self-consistent, all-electron, local density calculation for the partial density of states, total density of states and the charge analysis is also presented here.

Optical pumping of dipolar order in a coupled nuclear spin system

A possible mechanism for the direct generation of dipolar order in a coupled nuclear spin system by optical pumping is investigated theoretically. This work is motivated by recent optically pumped nuclear magnetic resonance experiments on single-crystal indium phosphide wafers, which have revealed that optical pumping can generate a state of nuclear spin dipolar order in a system of coupled spins without the application of radiofrequency fields or pulse sequences. The theory proceeds by evaluating the steady-state populations of the eigenstates of a coupled nuclear spin system when simultaneous nuclear and electron spin transitions are driven by fluctuating hyperfine couplings of the nuclei to an electron with a non-equilibrium spin polarization. In the case of two coupled spin-1/2 nuclei, substantial dipolar order results when the hyperfine couplings are of the dipolar, but not the Fermi contact, type.