Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “In2Se3”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

High pressure structural and lattice dynamics study of α-In2Se3

Layered α-In2Se3 has been studied using a combined in situ synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy study in a diamond anvil cell up to 60+ GPa, at room temperature. Helium, which remains fairly hydrostatic up to the highest pressure in this study, was used as the pressure-transmitting medium. The results from both experimental methods reveal a pressure-induced structural phase transition from α-In2Se3 to a monoclinic β'-In2Se3 structure at ≈1 GPa, in agreement with previous studies. Based on our detailed measurements using both experimental techniques and the F-f formalism, the β'-In2Se3 structure remains stable up to 45 GPa, without a clear indication of a phase transition toward the previously reported β-In2Se3 phase. Above this pressure, In2Se3 adopts a disordered solid-solution-like orthorhombic structure, phase IV. The results are discussed in comparison with the relevant previous studies of α-In2Se3 under pressure.

Feng, Shiyu↗
DOE OSTI2020

Materials Data on In2Se3 by Materials Project

In2Se3 crystallizes in the trigonal R3m space group. The structure is two-dimensional and consists of three In2Se3 sheets oriented in the (0, 0, 1) direction. there are two inequivalent In3+ sites. In the first In3+ site, In3+ is bonded to four Se2- atoms to form distorted corner-sharing InSe4 tetrahedra. There are one shorter (2.49 Å) and three longer (2.76 Å) In–Se bond lengths. In the second In3+ site, In3+ is bonded in a 6-coordinate geometry to six Se2- atoms. There are three shorter (2.70 Å) and three longer (3.42 Å) In–Se bond lengths. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a single-bond geometry to one In3+ atom. In the second Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent In3+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to six In3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on In2Se3 by Materials Project

In2Se3 is trigonal omega-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three In2Se3 sheets oriented in the (0, 0, 1) direction. In3+ is bonded in a distorted T-shaped geometry to three equivalent Se2- atoms. All In–Se bond lengths are 2.85 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to six equivalent Se2- atoms to form edge-sharing SeSe6 octahedra. All Se–Se bond lengths are 2.92 Å. In the second Se2- site, Se2- is bonded to three equivalent In3+ and three equivalent Se2- atoms to form a mixture of distorted edge and corner-sharing SeIn3Se3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on In2Se3 by Materials Project

In2Se3 crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one In2Se3 sheet oriented in the (0, 0, 1) direction. In3+ is bonded to six Se2- atoms to form a mixture of edge and corner-sharing InSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are three shorter (2.68 Å) and three longer (2.99 Å) In–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to six equivalent In3+ atoms to form edge-sharing SeIn6 octahedra. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent In3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on In2Se3 by Materials Project

In2Se3 crystallizes in the hexagonal P6_1 space group. The structure is three-dimensional. there are two inequivalent In3+ sites. In the first In3+ site, In3+ is bonded to four Se2- atoms to form InSe4 tetrahedra that share corners with two equivalent InSe4 tetrahedra, corners with four equivalent InSe5 trigonal bipyramids, and an edgeedge with one InSe5 trigonal bipyramid. There are a spread of In–Se bond distances ranging from 2.60–2.68 Å. In the second In3+ site, In3+ is bonded to five Se2- atoms to form InSe5 trigonal bipyramids that share corners with four equivalent InSe4 tetrahedra, an edgeedge with one InSe4 tetrahedra, and edges with two equivalent InSe5 trigonal bipyramids. There are a spread of In–Se bond distances ranging from 2.64–2.97 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three In3+ atoms. In the second Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three In3+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three In3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on In2Se3 by Materials Project

In2Se3 crystallizes in the hexagonal P6_5 space group. The structure is three-dimensional. there are two inequivalent In3+ sites. In the first In3+ site, In3+ is bonded in a 3-coordinate geometry to three Se2- atoms. There are a spread of In–Se bond distances ranging from 2.95–3.25 Å. In the second In3+ site, In3+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of In–Se bond distances ranging from 2.51–2.96 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three In3+ atoms. In the second Se2- site, Se2- is bonded in a 1-coordinate geometry to one In3+ and one Se2- atom. The Se–Se bond length is 2.44 Å. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to three In3+ and one Se2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Evidence for In-Plane Electrical Polarization in 3R-β’-In 2 Se 3 Thin Films Grown by Molecular Beam Epitaxy

β-In 2 Se 3 has been identified as a potential ferroelectric. This work describes the growth of β-In 2 Se 3 via molecular beam epitaxy along with a description of its properties, including the search for switchable polarization in 3R-β’-In2Se3. The thin-film morphology, crystal structure, and phase maps of β-In 2 Se 3 on Si(111) and Al 2 O 3 (0001) were evaluated by atomic force microscopy, X-ray diffraction, and Raman spectroscopy as a function of the atomic Se/In flux ratio and growth temperature. Smooth β-In 2 Se 3 thin films were successfully realized on Si(111) at a substrate temperature of 150 °C using a Se/In flux ratio of 5.7, as well as on Al 2 O 3 (0001) at 450 °C using a Se/In flux ratio of 5.5. Scanning transmission electron microscopy (STEM) confirms the 3R polytype of β-In 2 Se 3 in films on both substrates, with a minor disorder associated with the 2H polytype at the interface. Indications of in-plane Se atom displacements characteristic of the 3R-β’-In 2 Se 3 polytype were found by STEM and second harmonic generation analysis in films on Al 2 O 3 (0001), but not in films on Si(111). Furthermore, attempts at electrical polarization switching did not produce compelling evidence for ferroelectricity. Instead, electrical transport measurements demonstrated locally varying anisotropic responses with the applied electric fields along different in-plane directions, with some hysteresis associated with the trapping of charges.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Advanced Laser Processing of Materials--Fundamentals and Applications

Preparation of amorphous thin films in semiconductors and their transition to the crystalline phase may apply to switching devices. Surfaces of single crystal samples of bulk In2Se3 and thin films of InSe were treated using an excimer laser, and microscopic examination showed the treated portions of the surface had become amorphous. Film samples of InSe were laser-treated like the bulk samples. Examination of these treated flims showed shifts in the optical transmittance spectra as well as surface morphology changes.

amorphous thin films semiconductors crystalline ph↗
DOE OSTI2022

Structural Phase Transitions between Layered Indium Selenide for Integrated Photonic Memory

The primary mechanism of optical memoristive devices relies on phase transitions between amorphous and crystalline states. The slow or energy-hungry amorphous–crystalline transitions in optical phase-change materials are detrimental to the scalability and performance of devices. Leveraging an integrated photonic platform, nonvolatile and reversible switching between two layered structures of indium selenide (In 2 Se 3 ) triggered by a single nanosecond pulse is demonstrated. The high-resolution pair distribution function reveals the detailed atomistic transition pathways between the layered structures. With interlayer “shear glide” and isosymmetric phase transition, switching between the α- and β-structural states contains low re-configurational entropy, allowing reversible switching between layered structures. Broadband refractive index contrast, optical transparency, and volumetric effect in the crystalline–crystalline phase transition are experimentally characterized in molecular-beam-epitaxy-grown thin films and compared to ab initio calculations. Finally, the nonlinear resonator transmission spectra measure of incremental linear loss rate of 3.3 GHz, introduced by a 1.5 µm-long In 2 Se 3 -covered layer, resulted from the combinations of material absorption and scattering.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Wafer-scale growth of two-dimensional, phase-pure InSe

Two-dimensional (2D) indium monoselenide (InSe) has attracted significant attention as an ultrathin III–VI semiconductor with a combination of favorable attributes that are comparable to those of III–V semiconductors and van der Waals 2D transition-metal dichalcogenides. Nevertheless, there has been no demonstration of large-area synthesis of 2D InSe due to the complexity of the binary In-Se system and the difficulties in promoting lateral growth. Here, we report the polymorph-selective synthesis of epitaxial 2D InSe by metal-organic chemical vapor deposition (MOCVD) over 2-in wafers. We achieve polymorph-selective epitaxial growth of InSe on c-plane sapphire via flow modulation to control the Se/In ratio. The layer-by-layer growth allows thickness control with tunable optical properties comparable to those of bulk crystals. We also demonstrate gate-tunable electrical transport with a field-effect mobility comparable to that of single-crystalline flakes. Importantly, these results indicate that InSe grown by MOCVD could be an effective channel material for back-end-of-line integration in logic transistors.

2D materials↗