Indium Selenide Crystals Research Articles

Influence of Antimony doping on electrical and photoelectrical response in Indium Selenide crystals

Indium Selenide (InSe) is the most suitable photovoltaic conversion material with narrow band gap (1.3 eV) in the layered semiconductors. The optical and transport properties of InSe offer significant potential for promising applications in the modern era of electronics and photo-electronic devices. The aim is achieved by high electric conductivity of InSe crystals, SbxIn1−xSe (x= 0.00, 0.10, 0.15, 0.20) crystals was grown by direct vapour transport (DVT) technique. The chemical compositional and surface morphology properties of grown crystals were studied by energy dispersive X-ray analysis (EDAX) and scanning electron microscope (SEM) respectively. The hexagonal crystal structure of grown crystal has revealed by X-ray diffraction (XRD) spectra. The dopant concentration of antimony (Sb) was found to have a decreasing effect on the optical band gap and activation energy as calculated through absorption spectra and Arrhenius relations respectively. The photo-response parameters: growth-decay and trap-depth parameters have been obtained using growth-decay curve. These results confirm that SbxIn1−xSe crystal was collective applicant for electronic and optoelectronic devices.

Selective crystal growth of indium selenide compounds from saturated solutions grown in a selenium vapor

Indium selenide compounds are promising materials for energy conversion, spintronic applications, and chemical sensing. However, it is difficult to grow stoichiometric indium selenide crystals due to the high equilibrium selenium vapor pressure and the complicated phase equilibrium system of indium selenide compounds. In this paper, we apply a novel and convenient crystal growth method, in which the saturated solution is grown by the application of a selenium vapor. In this method, selenium vapor at a pressure higher than the saturated vapor pressure is applied to molten indium, such that the selenium continuously dissolves into the indium solution until the solubility at the growth temperature is reached; then a slow cooling process results in crystallization. The selenium dose is matched to its solubility so that indium selenide compounds can be selectively grown just by controlling the temperature without the need to consider the chemical ratio in the solution. The pressure of the vapor is controlled during the whole growth process so that any deviation from a stoichiometric composition in the crystal can be controlled. Both InSe and In2Se3 were successfully grown using this method, and we have investigated the growth mechanism and found the growth window for each compound. This study presents a novel and convenient approach to fabricating transitional metal chalcogenides without deficiencies in the chalcogen element.

Synthesis, characterization and photo-detection parameters of (Sb0.05In0.95)Se crystals

The antimony doped indium selenide crystals have been grown using Direct Vapour Transport (DVT) technique. The compositional, morphological, structural and photoconductive properties of (Sb0.05In0.95)Se crystal has been characterized by EDAX, SEM, XRD and I-V measurement analysis respectively. SEM image shows that (Sb0.05In0.95)Se crystal has layer by layer growth. The photo-current of (Sb0.05In0.95)Se crystal was measured as a function of various illumination intensity of 50, 75, 100, and 125 mW/cm2. The photo-response parameters: photo-current, responsivity, specific detectivity, and external quantum efficiency EQE (%) have been estimated. The photo current at the termination of illumination (I0), probability of escape of an electron from the trap per second (p) and trap depth (Et) have been studied and determined by the growth decay curve. It depends upon illumination intensity of incident light source. These characteristics makes (Sb0.05In0.95)Se crystal suitable candidate for efficient photo-electric devices.

Activating Silent Synapses in Sulfurized Indium Selenide for Neuromorphic Computing.

The transformation from silent to functional synapses is accompanied by the evolutionary process of human brain development and is essential to hardware implementation of the evolutionary artificial neural network but remains a challenge for mimicking silent to functional synapse activation. Here, we developed a simple approach to successfully realize activation of silent to functional synapses by controlled sulfurization of chemical vapor deposition-grown indium selenide crystals. The underlying mechanism is attributed to the migration of sulfur anions introduced by sulfurization. One of our most important findings is that the functional synaptic behaviors can be modulated by the degree of sulfurization and temperature. In addition, the essential synaptic behaviors including potentiation/depression, paired-pulse facilitation, and spike-rate-dependent plasticity are successfully implemented in the partially sulfurized functional synaptic device. The developed simple approach of introducing sulfur anions in layered selenide opens an effective new avenue to realize activation of silent synapses for application in evolutionary artificial neural networks.

The advancement of compelling Indium Selenide: synthesis, structural studies, optical properties and photoelectrical applications

Single crystals of Indium Selenide (InSe) were successfully grown by direct vapor transport method. The grown crystals were characterized by estimating their surface morphology, chemical composition, structural, optical and photoconductive properties using appropriate techniques. SEM image suggested that InSe crystal has layered-type surface without morphological defects. Also, the hexagonal structure of crystal has been confirmed by X-ray diffraction (XRD) spectra and selected area electron diffraction (SAED) pattern. The crystal exhibits high absorption coefficient (104 cm−1) in visible region and direct bandgap of 1.22 eV. The trap depth parameters and photoconductivity parameters were determined by the growth-decay curve and they depend upon illumination intensity, temperature and wavelength of incident light. The grown InSe crystals have excellent photoconductive properties and hence can be utilized in different photoelectrical applications.

Exceptional plasticity in the bulk single-crystalline van der Waals semiconductor InSe.

Inorganic semiconductors are vital for a number of critical applications but are almost universally brittle. Here, we report the superplastic deformability of indium selenide (InSe). Bulk single-crystalline InSe can be compressed by orders of magnitude and morphed into a Möbius strip or a simple origami at room temperature. The exceptional plasticity of this two-dimensional van der Waals inorganic semiconductor is attributed to the interlayer gliding and cross-layer dislocation slip that are mediated by the long-range In-Se Coulomb interaction across the van der Waals gap and soft intralayer In-Se bonding. We propose a combinatory deformability indicator (Ξ) to prescreen candidate bulk semiconductors for use in next-generation deformable or flexible electronics.

Indium selenide: an insight into electronic band structure and surface excitations

We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.

Observing the interplay between surface and bulk optical nonlinearities in thin van der Waals crystals.

Van der Waals materials, existing in a range of thicknesses from monolayer to bulk, allow for interplay between surface and bulk nonlinearities, which otherwise dominate only at atomically-thin or bulk extremes, respectively. Here, we observe an unexpected peak in intensity of the generated second harmonic signal versus the thickness of Indium Selenide crystals, in contrast to the quadratic increase expected from thin crystals. We explain this by interference effects between surface and bulk nonlinearities, which offer a new handle on engineering the nonlinear optical response of 2D materials and their heterostructures.

A new crystal: layer-structured rhombohedral In3Se4

A new layer-structured rhombohedral In3Se4 crystal was synthesized by a facile and mild solvothermal method. Detailed structural and chemical characterizations using transmission electron microscopy, coupled with synchrotron X-ray diffraction analysis and Rietveld refinement, indicate that In3Se4 crystallizes in a layered rhombohedral structure with lattice parameters of a = 3.964 ± 0.002 Å and c = 39.59 ± 0.02 Å, a space group of Rm, and with a layer composition of Se–In–Se–In–Se–In–Se. The theoretical modeling and experimental measurements indicate that the In3Se4 is a self-doped n-type semiconductor. This study not only enriches the understanding on crystallography of indium selenide crystals, but also paves a way in the search for new semiconducting compounds.

Intercalation Induced Electret Effect in GaSe and InSe Crystals: Experiment and Theory

Intercalation of gallium and indium selenide crystals by nickel initiates their electret polarization. The effect manifests itself at small concentrations of the intercalant. Temperature dependences of dielectric permittivity for both crystals demonstrate peaks in the same region of concentration. The effect is presumably connected with the ordering of local quasi-dipoles caused by the redistribution of intercalant atoms between octahedral and two tetrahedral positions. It is shown that a microscopic four-state model is able to reproduce a peak-like behaviour of the polarization at change of the intercalant chemical potential (concentration) and peculiarities of temperature dependences of the transverse dielectric susceptibility.

Effect of rare-earth doping on the electrical properties of InSe single crystals

The effect of rare-earth doping (R = Gd, Dy, Ho) to different levels (0, 10−5, 10−4, 10−3, 10−2, and 10−1 at %) on threshold switching and low-frequency current oscillations in single crystals of indium selenide, a layered III–VI semiconductor, has been studied in broad ranges of temperatures (77–400 K), wavelengths (0.30–3.50 μm), and illuminances (up to ∼102 lx). The results are interpreted in terms of the anisotropic chemical bonding in n-InSe and its response to rare-earth doping.

Oxide-p-InSe heterostructures with improved photoelectric characteristics

Heterostructures consisting of p-InSe and native oxide were formed by thermal oxidation of indium selenide crystals in air. Long-term (for 1–5 days) oxidation of InSe substrates at 450°C leads to changes in both the photosensitivity spectral band and the photoelectric parameters of the heterostructures compared to samples oxidized for 5–15 min. These changes are due to the layer-by-layer formation of additional oxide phases on the semiconductor surface. For the best heterostructures, the open-circuit voltage attains 0.6 V and the short-circuit current density is 30–35 mA/cm2 under saturation conditions. The electrical characteristics of the heterostructures are distorted by the effect of series resistance, which complicates the determination of the potential-barrier height and the mechanism of current flow through the barrier.

Preparation, properties, and applications of laser-prepared intercalated structures in nanoelectronics

Experimental investigation of the structure and electrical properties of layered gallium selenide and indium selenide crystals laser-intercalated by copper and gallium is discussed.

Electric-Field-Controlled Attenuator for Near IR Laser Radiation

A design of an attenuator for IR laser radiation and the method for its manufacturing are described. The device is based on the electric-field-induced shift of the optical absorption edge of indium selenide crystals. It is shown that InSe with a resistivity of 0,2-200 Ω cm and applied electric field of 102 V/cm reduces the intensity of YAG:Nd+3 laser radiation (λ = 1,06 μm, pulse duration of 10 ns and power of 10 MW) by more than two orders of magnitude. The physical mechanism of the anomalous large shift of the absorption edge is given. The device can also be efficiently used as a cut-off filter for near IR range of spectrum.

Silver intercalated III–VI compounds

The intercalation of silver into layered semiconductors of III–VI family is investigated for the first time. Single crystals of indium selenide and indium sesquiselenide are intercalated by two methods: a classical electrochemical one and a pulsed electric field method. Kinetic parameters of the mobile ions (silver) were measured at room temperature. Low values of the chemical diffusion coefficient are observed and variations of D as a function of the silver concentration are presented.

Electron diffraction study of melt-grown InSe crystals

Electron diffraction has been performed on thin crystals of indium selenide, cleaved from ingots grown from stoichiometric and nonstoichiometric melt by the Bridgman-Stockbarger method. The analysis of the selected area diffraction patterns has shown the presence of two phases, whose lattice parameters have been calculated. The stacking sequence of the polytypes has been observed through the moire patterns.

Mecanisme du transport chimique du seleniure d'indium par l'iode

Electronic and Raman spectroscopies allow to determine the gaseous species which appear at the time of the preparation of single crystals of indium selenide In 2Se 3 by chemical transport with iodine. The gaseous phase of the system contains the following species: I 2, I, Se n ( n = 2, 3, 5, 6, 7, 8) and InI above 650°C and besides InI 3 below 650°C. The determination of the gaseous pressure allows to calculate the thermodynamic constants of the two equilibria: In 2 Se 3(S) + I 2(g)⇌2 InI(g) + 3 2 Se 2(g) In 2 Se 3(S) + 3 I 2(g)⇌2 InI 3(g) + 3 2 Se 2(g)

Preparation and electrical properties of InSe

Single crystals of Indium Selenide are prepared by vapour growth technique as it is difficult to prepare large single crystals by vertical Bridgman technique. The effect of stochiometric changes an...