Temperature effects on the structural phase transitions of gallium phosphide

Ribeiro-Silva, C. I.; Picinin, A.; Rino, José Pedro; Menezes, Marcos G.; Capaz, Rodrigo B.

doi:10.1016/j.commatsci.2019.02.010

Cited by 9 publications

(2 citation statements)

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“…To simulate the atomic behavior of GaP in CMDS, a force field based on the Vashista potential energy function is available in the literature [16]. This force field was used to describe GaP phase transformations under different pressures and temperatures under pure hydrostatic pressure [17,18]. Moreover, this potential was successfully implemented to simulate GaP nanoindentation by Tavares et al [15].…”

Section: Introductionmentioning

confidence: 99%

Simulation of gallium phosphide cutting mechanism in ductile regime using molecular dynamics

Reis Pedreira Muniz Tavares,

Rolón,

Christian Bernhard Kober

et al. 2023

Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XX

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Gallium Phosphide (GaP) is a semiconductor with advantageous optical properties for near- and middle infrared optical systems. However, optical applications of GaP are limited by its current low machinability. To cut brittle semiconductors such as GaP and generate optical quality surfaces, it is necessary to induce a High-Pressure Phase Transformation (HPPT) so that a phase is formed that behaves ductile when machined. Along the cutting process this can be achieved by applying a negative rake angle. Otherwise, cracks will appear on the machined surface, worsening its optical capabilities. A HPPT of GaP happens at an atomic scale when a zincblende structure changes into a β-tin one. The β-tin structure behaves ductile and is metastable. Hence, the metastable β-tin phase cannot be observed during the cutting process. Therefore, atomistic simulation, such as Classic Molecular Dynamics Simulation (CMDS), is required to study the machinability under HPPT. In this work, CMDS were used to analyze GaP cutting mechanisms. A diamond tool was modelled with a cutting edge radius rβ = 10 nm, rake angle γ = -20 º, and clearance angle α = 10 º. The cut was performed with a depth of cut ap = 12 nm along the [100]-direction in a zincblende GaP workpiece. Stacking faults were found on the shear zone, {111}-planes, by two different post processes approaches. HPPT was found in the deformation zone only. A stagnation zone was found in front of the cutting edge proceeding a crack nucleation.

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Section: Introductionmentioning

confidence: 99%

Simulation of gallium phosphide cutting mechanism in ductile regime using molecular dynamics

Reis Pedreira Muniz Tavares,

Rolón,

Christian Bernhard Kober

et al. 2023

Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XX

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“…Gallium phosphide (GaP) is an indirect III/V compound semiconductor with a band gap E g of approximately 2.25 eV at room temperature. [13,14] It crystallizes in the zinc blende structure [13,15] with the cubic space group T 2 d . GaP has two atoms per primitive cell, resulting in three-fold degenerate acoustic and optical phonon modes at Γ.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the optical phonon reflection band in GaP

Samarasingha,

Zollner

2021

Preprint

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We explore the effect of temperatures between 80 and 720 K on the energy and linewidth of zonecenter transverse (TO) and longitudinal (LO) optical phonons in bulk gallium phosphide (GaP) using Fourier transform infrared ellipsometry from 0.03 to 0.60 eV. We extract the optical phonon parameters of GaP by fitting the ellipsometric angles with the Lowndes-Gervais model, which applies two different broadening parameters to the TO and LO phonons. In GaP, the two-phonon density of states is larger for the decay of TO phonons than for LO phonons. Therefore, we observed a larger TO phonon broadening (compared to the LO phonon) and an asymmetric reststrahlen line shape. This would lead to a negative imaginary part of the dielectric function just above the LO phonon energy, but the addition of two-phonon absorption avoids this. We find a temperature dependent redshift and broadening of TO and LO phonons with increasing temperature due to thermal expansion and anharmonic phonon-phonon scattering, involving three and four phonon decay processes. We also investigate the temperature-dependence of the high-frequency dielectric constant. Its variation is explained by thermal expansion and the temperature dependence of the Penn gap.

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