Indium Phosphide Crystals Research Articles

Damage and removal behaviors of indium phosphide crystals involved in ultrasonic vibration-assisted AFM machining

Indium phosphide (InP) crystals exhibit a propensity for brittle damage during machining, categorizing them as challenging materials due to their inherent brittleness and pronounced anisotropy. Atomic force microscopy (AFM) machining serves as a crucial approach for achieving low-damage removal of such brittle crystals. Molecular dynamics simulations were conducted to investigate the vibration-assisted AFM machining of InP crystals, systematically exploring the effects of scratching force, stress distribution, and subsurface damage. The findings revealed that plastic deformation of InP crystals during vibration-assisted AFM scratching was primarily governed by mechanisms including stress-induced amorphization transitions, phase transformations, dislocations, stacking faults, and lattice distortions. Compared to conventional AFM machining, vibration-assisted AFM machining had a smaller average contact area and maintained a periodic movement pattern of contact-separation. This induced the change of chip removal from piling up in front of the cutting tool to uniform flow to both sides. Employing appropriate vibration parameters in vibration-assisted AFM significantly diminished the scratching force, stress, dislocation length, and subsurface damage depth. These results not only elucidate the material removal and damage mechanisms of InP crystals at atomic and close-to-atomic scales, but also offer theoretical guidance for parameter optimization in the vibration-assisted AFM machining of other soft and brittle crystals.

Space-confined synthesis of two-dimensional InP crystals for high-performance self-powered Schottky photodiode

Atomic-thin III-V semiconductors with nanometer thickness have emerge as promising candidate for diverse applications in optoelectronics. In this work, by using a space-confine approach, ultra-thin indium phosphide (InP) crystals were obtained with thickness scaled down 10 nm, which demonstrate an extremely giant second harmonic generation (SHG) susceptivity up to 2.05 × 10−9 m/V under 1064 nm excitation, among the best of reported two-dimensional semiconductors. In addition, a high-performance Schottky photodiode with asymmetric electrical contact was implemented. The self-powered device exhibits a high responsivity of 15.3 mA W−1 and a detectivity of 1.94 × 1010 Jones under 532 nm light illumination, revealing a high on/off ratio of photocurrent exceeding 103 under zero bias, accompanied by rapid response times of only milliseconds. The results offer a streamlined avenue to develop ultrathin III-V semiconductor for high-performance photodetectors in future 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.

Thick-walled coating in Gunn diode for measuring of electromagnetic radiation power in microwave range

In the introduction, the analysis of the physical basis for the operation of the semiconductor Gunn diode is carried out and the issues that should be resolved in substantiation of the basic physical principles of this diode operation are stated. At applied voltages of up to 0.6 V to a gallium arsenide or indium phosphide Gunn diode, free electrons appear in the conduction band of aluminum as a result of ionization of negative ions of gallium or indium atoms. At voltages from 0.6 to 2.0 V, free electrons appear in the aluminum conduction band as a result of ionization of negative ions of arsenic atoms, and at voltages from 0.6 to 3.0 V — phosphorus. The formation of negative gallium or indium ions is caused by electron capture directly from the aluminum base, while the formation of negative arsenic or phosphorus ions is mainly due to spontaneous electron transfer from the aluminum conduction band and from the negative gallium or indium ions. Electric current flows only over the surface of a gallium arsenide or indium phosphide crystal. The frequency of electric current oscillation is defined by the voltage applied to the Gunn diode and the thickness of the gallium arsenide or indium phosphide crystal. Determination of the power of microwave signals by the Gunn diode is carried out by applying a constant voltage between the cathode and the anode, which provides the frequency of current oscillation equal to the frequency of the measured microwave signal. The maximum radiation power in microwave wavelengths measured by the Gunn diode is determined by the equality of the electromagnetic wave perturbation energy and the electron affinity energy of gallium or indium atoms in the vicinity of the aluminum conduction band.

Geant4 simulation of neutron displacement damage effect in InP

As the second-generation compound semiconductor material, indium phosphide (InP) has strong irradiation resistance and high photoelectric conversion efficiency. It has advantages in the field of photonics and radio frequency. In atmospheric space, high-energy cosmic rays enter into the earth’s atmosphere and interact with nitrogen (N), oxygen (O) and other elements to produce secondary cosmic rays. The irradiation particles in the atmosphere are mainly neutrons because the penetration of charged particles is weak. The InP semiconductor devices are affected by atmospheric neutron irradiation of various energy from all directions, which results in the internal defects in InP crystals, the degradation of device performance and the reduction of device lifetime. In this paper, Monte Carlo simulation software Geant4 is used to simulate the neutron irradiation effect, and the initial state distribution of displacement damage caused by neutrons with different energy is obtained, including the distribution of non-ionized energy loss (NIEL) with depth, the relationship between NIEL and the energy of incident neutrons, and the type, number and energy of primary knock-on atoms (PKA). The results show that 1) the NIEL is uniformly distributed when material thickness is on the order of μm and for the material thickness on the order of cm and more, the NIEL decreases as the depth increases and can be reduced to zero when the target material is thick enough; 2) by analyzing the NIEL produced by 1–20 MeV neutrons incident on 3-μm InP and their distribution with depth, it is found that the NIEL first increases and then decreases with incident neutron energy increasing. This trend is caused mainly by PKA produced through the inelastic scattering reaction; 3) by analyzing the type and the energy of PKA produced by 1–20 MeV neutrons incident on 3 μm InP, it is found that the PKA of In/P accounts for a large proportion, which causes displacement damage mainly, and the higher the neutron energy, the richer the variety of PKA is and the greater the maximum kinetic energy of PKA, but the PKAs mainly distribute in the low energy part. The present research has theoretical and guiding value for the long-term application of InP-based 5G devices in atmospheric neutron irradiation environment.

Получение терагерцового излучения в кристаллах InP : Fe за счет решеточной нелинейности второго порядка

In this paper, we experimentally demonstrate the generation of the second harmonic radiation of the gyrotron with an operating frequency of 263 GHz due to the second order lattice nonlinearity in indium phosphide crystals doped with ferrum. It is shown that the second harmonic radiation can be used for magnetospectroscopy of semiconductor nanostructures. We discuss the possibility of generating a difference frequency in these crystals when excited by two sources of the mid-IR range with a close wavelength.

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.

Second-Harmonic Generation of Subterahertz Gyrotron Radiation by Frequency Doubling in InP:Fe and Its Application for Magnetospectroscopy of Semiconductor Structures

The possibility of obtaining intense terahertz radiation due to second-order lattice nonlinearity in indium-phosphide crystals doped with iron is discussed. As a source of radiation, subterahertz gyrotrons are considered. It is shown that the efficiency of frequency doubling can reach 3%, which opens up the possibility for developing a new generation of terahertz radiation sources. The possibility of applying second-harmonic radiation for the magnetospectroscopy of semiconductor structures with quasi-Dirac dispersion is demonstrated.

Enhancement of the Inelastic Nuclear Interaction Rate in Crystals via Antichanneling.

The interaction rate of a charged particle beam with the atomic nuclei of a target varies significantly if the target has a crystalline structure. In particular, under specific orientations of the target with respect to the incident beam, the probability of inelastic interaction with nuclei can be enhanced with respect to the unaligned case. This effect, which can be named antichanneling, can be advantageously used in the cases where the interaction between beam and target has to be maximized. Here we propose to use antichanneling to increase the radioisotope production yield via cyclotron. A dedicated set of experimental measurements was carried out at the INFN Legnaro Laboratories with the AN2000 and CN accelerators to prove the existence of the antichanneling effect. The variation of the interaction yield at hundreds of keV to MeV energies was observed by means of sapphire and indium phosphide crystals, achieving an enhancement of the interaction rate up to 73% and 25%, respectively. Such a result may pave the way to the development of a novel type of nozzle for the existing cyclotrons, which can exploit crystalline materials as targets for radioisotope production, especially to enhance the production rate for expensive prime materials with minor upgrades of the current instrumentation.

Получение второй гармоники излучения субтерагерцовых гиротронов при удвоении частоты в InP : Fe и ее использование для магнитоспектроскопии полупроводниковых структур

AbstractThe possibility of obtaining intense terahertz radiation due to second-order lattice nonlinearity in indium-phosphide crystals doped with iron is discussed. As a source of radiation, subterahertz gyrotrons are considered. It is shown that the efficiency of frequency doubling can reach 3%, which opens up the possibility for developing a new generation of terahertz radiation sources. The possibility of applying second-harmonic radiation for the magnetospectroscopy of semiconductor structures with quasi-Dirac dispersion is demonstrated.

Laser/Electron Irradiation on Indium Phosphide (InP) Semiconductor: Promising Pathways to In Situ Formation of Indium Nanoparticles

AbstractIn the current study, whether femtosecond laser and electron beam irradiation of indium phosphide (InP) are “green,” fast, and effective methods to produce metallic In nanoparticles is probed. High‐resolution transmission electron microscopy and energy‐dispersive X‐ray spectroscopy are employed to investigate the formation and growth of In nanoparticles on InP. Density functional theory and quantum theory of atoms in molecules calculations are employed to reveal the nature of formation of In nanoparticles under electron beam irradiation. These results expand the fundamental understanding of the atomic processes underpinning the mechanism of In−P bond rupture during the transformation process induced by the electron irradiation of the InP crystal by increasing the total number of electrons in the bulk structure.

Chemical Bond Formation and Rupture Processes: An Application of DFT–Chemical Pressure Approach

Very recently, we have analyzed the nature of chemical interactions in a wide variety of molecules and materials using the chemical pressure (CP) approach. We have shown how this newly developed formalism can be used to identify and visualize different types of chemical bonds based on the attractive and repulsive forces between the constitutive atoms of molecules and materials. In this article, we illustrate the capability of the CP approach to clearly track the bond formation and rupture processes in crystalline solids. Using the indium phosphide crystal as a model system, the evolution of its chemical bonding network is investigated in two different phenomena: (i) along a pressure-induced phase transition mechanism and (ii) after electron beam irradiation of the unit cell. The CP maps show distinctive features related to the local atomic interactions in the crystal structure, providing insights into the chemical nature of any distorted/defective structure throughout these transformation processes. This ...

Research into regularities of pore formation on the surface of semiconductors

A general procedure is devised to control the process of formation of porous layers on semiconductor surfaces by the method of electrochemical etching. When controlling the process of pore formation on the surface of crystal, it is necessary to consider: conditions of pore formation, requirements that are put forward to quality of the obtained nanostructures, and mechanisms that underlie the process of pore formation. It is shown that the built scheme could be used for different cases of the synthesis of nanostructured semiconductors. We investigated the processes that underlie pore formation and define morphological properties of nanostructures. A thermodynamic analysis of processes at the boundary of contact semiconductor–electrolyte was performed. We examined a relative drop in potential in the Helmholtz layer, which is an important characteristic of the process of pore formation on the surface of crystal. Main morphological criteria are selected of quality of porous nanostructures for their application in solar batteries. These include diameter and depth of the pore, a degree of porosity of the surface of a nanostructured crystal. Taking into account these criteria, we received porous spaces on the surface of semiconductors A3V5 that could be used for solar cells. We determined the value of boundary voltage of the early pore formation for semiconductors of group A3V5 during etching in the electrolyte HF:C2H5OН:H2O=1:2:1 for 15 min. It was established that at chosen conditions of etching. the largest capacity to pore formation is displayed by crystals of indium phosphide. The results obtained demonstrate that at the same conditions of etching semiconductors possess different ability to form pores

Morphological and spatial control of InP growth using closed-space sublimation

Scalable growth of high quality III-V semiconductor thin films on non-epitaxial substrates is of profound interest for photovoltaic applications. Here, we demonstrate growth of indium phosphide (InP) crystals directly on metal foils using closed-space sublimation (CSS) method. CSS allows effective transfer of source material to the substrate due to a small (∼2 mm gap between source and substrate) sublimation space. The crystallization kinetics are found to be dependent on the substrate temperature and pressure of the system. Importantly, experiments revealed that both InP nanowires and polycrystalline films could be obtained by tuning the growth conditions. Furthermore, utilizing a silicon dioxide mask, selective nucleation of InP on metal substrates was obtained. Photoluminescence measurements depict the high optical quality of the CSS grown InP.

Spectroscopy of ytterbium-doped InP under high hydrostatic pressure

The results of high-pressure low-temperature optical measurements in diamond-anvil cell of bulk indium phosphide crystals doped with Yb are reported. The observed initial increase in energy of $f\text{\ensuremath{-}}f$ intrashell transitions between the ${^{2}F}_{5/2}$ excited and ${^{2}F}_{7/2}$ ground levels at pressure up to 6 GPa is interpreted as a result of a linear increase in the spin-orbit parameter of ${\text{Yb}}^{3+}$ ions with pressure coefficient equal to $0.0059\text{ }{\text{cm}}^{\ensuremath{-}1}/\text{GPa}$ due to the covalency effects and mixing of the ${\text{Yb}}^{3+}$ and phosphorus wave functions. Above 6 GPa the pressure dependences of the peak positions of all the luminescence lines flatten out and the values of pressure coefficients strongly decrease. A tentative explanation is provided in terms of the $f$ levels of ${\text{Yb}}^{3+}$ approaching of the top of the valence band of InP crystal host, which limits further increase in $f\text{\ensuremath{-}}f$ intrashell transitions energies above 6 GPa pressure.

Nonlinear model-based control of the Czochralski process I: Motivation, modeling and feedback controller design

This paper presents a new approach for model-based control of the Czochralski process. The main idea is not to rely on a complex mathematical model of the overall process. Such a model usually suffers from many unknown parameters, boundary and initial conditions making the control system not robust. Instead, only those parts of the process are modeled the parameters of which are known with sufficient accuracy and the structure of which is sufficiently precise. From this model a nonlinear model-based controller is derived as the core of the proposed control system. It is used in combination with conventional PID controllers. Doing so, tracking of crystal diameter and growth rate trajectories is realized with a lot of model knowledge included in the control system. Thus, its performance is improved greatly. The usefulness of the approach is proven by several experimental results from growth of gallium-arsenide (GaAs) and indium-phosphide (InP) crystals.

Nanoscale dislocation patterning by scratching in an atomic force microscope

The nature of nanoscratching as a lithographic technique for site-selective generation of dislocations is investigated for use in the growth of nanostructures. Linear arrays of dislocations have been selectively introduced into (001) indium phosphide crystals by dragging a diamond tip in an atomic force microscope. The nature of plastic deformation is found to depend on the scratch direction. For ⟨110⟩ directions, anisotropic butterflylike structures with mostly screw dislocations indicate rotational motion in the vicinity of the advancing tip. For ⟨100⟩ directions, the dislocations do not propagate far from the surface, possibly due to interlocking between dislocations on different slip planes, with a surface morphology suggesting melting of the near surface region by frictional heat. These results indicate that growth of nanostructures should be highly dependent on the direction of the nanoscratch.

Formation of InP nanoparticles by laser ablation in an aqueous environment

Indium phosphide (InP) semiconductor nanoparticles were obtained by laser ablation of a crystalline wafer in water. The transmission electron microscopy micrographs of the nanoparticles show that their size is in the range of 100 nm. In the Raman spectrum of the nanoparticles, the characteristic peaks of InP have been observed in the vicinity of 300 and 340 cm −1. The binding energies as measured from the X-ray photoemission spectra are consistent with values for InP crystal as well as indium oxides.

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.

Magnetic and optical properties of ytterbium-doped indium phosphide crystals

The intimate relation connecting the magnetic and optical properties of ytterbium-doped indium phosphide is studied under the conditions of local magnetic ordering and compensation of spin correlations by electron-vibration interaction. An analysis of the temperature dependences of the static magnetic susceptibility and photoluminescence spectra shows that the impurity magnetism of InP(Yb) crystals originates from the presence of antiferromagnetically ordered Yb2O3 quasi-molecules, which transfer to a ferromagnetically ordered state in the vicinity of shallow donors by capturing a donor electron or compete to form regions of local magnetic ordering (bound spin polarons). In both cases, the s-f exchange constants, as derived from the temperature dependences of the static magnetic susceptibility, are found to be anomalously large, apparently because of the spin correlations being efficiently compensated by electron-vibration interaction. In addition, due to the s-f exchange, an exchange-coupled deep level of the ferromagnetically ordered Yb2O3 quasi-molecule arises in the band gap of indium phosphide. The formation of this level simulates Auger recombination of nonequilibrium carriers, which is responsible for enhancement of the intracenter photoluminescence of Yb3+ ions.