Massive-scale molecular dynamics of ion-irradiated III-V compound semiconductors at the onset of nanopatterning

Michael A. Lively, Brandon Holybee, Michael Toriyama, Jean Paul Allain

Research output: Contribution to journalArticle

Abstract

Large-scale atomistic computational modeling is critical to developing a fundamental understanding of the driving mechanisms behind ion beam-induced pattern formation on III-V compound semiconductor surfaces. Existing theoretical efforts fail to account for the existence of compositional depth profiles, as observed in experiments, which evolve over time and contribute to the development of lateral compositional instabilities. Another critical knowledge gap in existing theories is the a priori selection of ion-driven compositional mechanisms, so that different models predict the same surface morphology for radically different surface compositions. Atomistic simulations can elucidate key ion-induced compositional mechanisms leading to nonequilibrium compositional depth profiles. Such simulations must be performed on large length scales to enable connection of depth compositional mechanisms to lateral instabilities which ultimately drive patterning. To address these essential knowledge gaps, a 100×100nm2 GaSb surface was constructed for molecular dynamics simulations with altered composition based on experimental data at the pattern threshold fluence. The surface was then bombarded with 500eV Kr+ ions to a differential fluence of 8.4×1013 cm-2. In Ga-enriched (Sb-enriched) regions, clusters of Ga (Sb) are observed to form. While the Ga clusters remain amorphous, Sb clusters rapidly crystallize. The crystallization is not directly ion-induced but rather an intrinsic material behavior of pure Sb in response to the ion-induced compositional instability in the surface. To elucidate the ion-driven compositional changes leading to this state, 25×25nm2 "pristine" 50-50 GaSb crystalline surfaces were irradiated with 500eV Ne+, Ar+, and Kr+ to fluences on the order of 1016 cm-2. The ion-induced displacement cascade tends to lead to formation of Sb nanoclusters, while Ga rarely forms clusters but readily bonds to the Sb clusters. While initially the clustering behavior is the same for all ion species, for continued Kr+ irradiation the clusters become less prevalent within the material surface.

Fingerprint

ions
Ions
fluence
simulation
molecular dynamics
profiles
Molecular dynamics
Semiconductor materials
nanoclusters
cascades
ion beams
crystallization
irradiation
thresholds
Nanoclusters
Surface structure
Ion beams
Surface morphology
Crystallization
Irradiation

Keywords

  • III-V semiconductors
  • Ion beam nanosynthesis
  • Molecular dynamics
  • Nanopatterning

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

Cite this

@article{ed51f3f489f94d91b592aff994191b64,
title = "Massive-scale molecular dynamics of ion-irradiated III-V compound semiconductors at the onset of nanopatterning",
abstract = "Large-scale atomistic computational modeling is critical to developing a fundamental understanding of the driving mechanisms behind ion beam-induced pattern formation on III-V compound semiconductor surfaces. Existing theoretical efforts fail to account for the existence of compositional depth profiles, as observed in experiments, which evolve over time and contribute to the development of lateral compositional instabilities. Another critical knowledge gap in existing theories is the a priori selection of ion-driven compositional mechanisms, so that different models predict the same surface morphology for radically different surface compositions. Atomistic simulations can elucidate key ion-induced compositional mechanisms leading to nonequilibrium compositional depth profiles. Such simulations must be performed on large length scales to enable connection of depth compositional mechanisms to lateral instabilities which ultimately drive patterning. To address these essential knowledge gaps, a 100×100nm2 GaSb surface was constructed for molecular dynamics simulations with altered composition based on experimental data at the pattern threshold fluence. The surface was then bombarded with 500eV Kr+ ions to a differential fluence of 8.4×1013 cm-2. In Ga-enriched (Sb-enriched) regions, clusters of Ga (Sb) are observed to form. While the Ga clusters remain amorphous, Sb clusters rapidly crystallize. The crystallization is not directly ion-induced but rather an intrinsic material behavior of pure Sb in response to the ion-induced compositional instability in the surface. To elucidate the ion-driven compositional changes leading to this state, 25×25nm2 {"}pristine{"} 50-50 GaSb crystalline surfaces were irradiated with 500eV Ne+, Ar+, and Kr+ to fluences on the order of 1016 cm-2. The ion-induced displacement cascade tends to lead to formation of Sb nanoclusters, while Ga rarely forms clusters but readily bonds to the Sb clusters. While initially the clustering behavior is the same for all ion species, for continued Kr+ irradiation the clusters become less prevalent within the material surface.",
keywords = "III-V semiconductors, Ion beam nanosynthesis, Molecular dynamics, Nanopatterning",
author = "Lively, {Michael A.} and Brandon Holybee and Michael Toriyama and Allain, {Jean Paul}",
year = "2016",
month = "12",
doi = "10.1016/j.nimb.2017.04.047",
journal = "Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms",
issn = "0168-583X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Massive-scale molecular dynamics of ion-irradiated III-V compound semiconductors at the onset of nanopatterning

AU - Lively,Michael A.

AU - Holybee,Brandon

AU - Toriyama,Michael

AU - Allain,Jean Paul

PY - 2016/12/11

Y1 - 2016/12/11

N2 - Large-scale atomistic computational modeling is critical to developing a fundamental understanding of the driving mechanisms behind ion beam-induced pattern formation on III-V compound semiconductor surfaces. Existing theoretical efforts fail to account for the existence of compositional depth profiles, as observed in experiments, which evolve over time and contribute to the development of lateral compositional instabilities. Another critical knowledge gap in existing theories is the a priori selection of ion-driven compositional mechanisms, so that different models predict the same surface morphology for radically different surface compositions. Atomistic simulations can elucidate key ion-induced compositional mechanisms leading to nonequilibrium compositional depth profiles. Such simulations must be performed on large length scales to enable connection of depth compositional mechanisms to lateral instabilities which ultimately drive patterning. To address these essential knowledge gaps, a 100×100nm2 GaSb surface was constructed for molecular dynamics simulations with altered composition based on experimental data at the pattern threshold fluence. The surface was then bombarded with 500eV Kr+ ions to a differential fluence of 8.4×1013 cm-2. In Ga-enriched (Sb-enriched) regions, clusters of Ga (Sb) are observed to form. While the Ga clusters remain amorphous, Sb clusters rapidly crystallize. The crystallization is not directly ion-induced but rather an intrinsic material behavior of pure Sb in response to the ion-induced compositional instability in the surface. To elucidate the ion-driven compositional changes leading to this state, 25×25nm2 "pristine" 50-50 GaSb crystalline surfaces were irradiated with 500eV Ne+, Ar+, and Kr+ to fluences on the order of 1016 cm-2. The ion-induced displacement cascade tends to lead to formation of Sb nanoclusters, while Ga rarely forms clusters but readily bonds to the Sb clusters. While initially the clustering behavior is the same for all ion species, for continued Kr+ irradiation the clusters become less prevalent within the material surface.

AB - Large-scale atomistic computational modeling is critical to developing a fundamental understanding of the driving mechanisms behind ion beam-induced pattern formation on III-V compound semiconductor surfaces. Existing theoretical efforts fail to account for the existence of compositional depth profiles, as observed in experiments, which evolve over time and contribute to the development of lateral compositional instabilities. Another critical knowledge gap in existing theories is the a priori selection of ion-driven compositional mechanisms, so that different models predict the same surface morphology for radically different surface compositions. Atomistic simulations can elucidate key ion-induced compositional mechanisms leading to nonequilibrium compositional depth profiles. Such simulations must be performed on large length scales to enable connection of depth compositional mechanisms to lateral instabilities which ultimately drive patterning. To address these essential knowledge gaps, a 100×100nm2 GaSb surface was constructed for molecular dynamics simulations with altered composition based on experimental data at the pattern threshold fluence. The surface was then bombarded with 500eV Kr+ ions to a differential fluence of 8.4×1013 cm-2. In Ga-enriched (Sb-enriched) regions, clusters of Ga (Sb) are observed to form. While the Ga clusters remain amorphous, Sb clusters rapidly crystallize. The crystallization is not directly ion-induced but rather an intrinsic material behavior of pure Sb in response to the ion-induced compositional instability in the surface. To elucidate the ion-driven compositional changes leading to this state, 25×25nm2 "pristine" 50-50 GaSb crystalline surfaces were irradiated with 500eV Ne+, Ar+, and Kr+ to fluences on the order of 1016 cm-2. The ion-induced displacement cascade tends to lead to formation of Sb nanoclusters, while Ga rarely forms clusters but readily bonds to the Sb clusters. While initially the clustering behavior is the same for all ion species, for continued Kr+ irradiation the clusters become less prevalent within the material surface.

KW - III-V semiconductors

KW - Ion beam nanosynthesis

KW - Molecular dynamics

KW - Nanopatterning

UR - http://www.scopus.com/inward/record.url?scp=85018755862&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85018755862&partnerID=8YFLogxK

U2 - 10.1016/j.nimb.2017.04.047

DO - 10.1016/j.nimb.2017.04.047

M3 - Article

JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

T2 - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

SN - 0168-583X

ER -