Composite GaN-C-Ga ("GaCN") Layers with Tunable Refractive Index

Sourish Banerjee, Arnoud J. Onnink, Satadal Dutta, Antonius A.I. Aarnink, Dirk J. Gravesteijn, Alexey Y. Kovalgin*

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    2 Citations (Scopus)

    Abstract

    This article describes novel composite thin films consisting of GaN, C, and Ga (termed "GaCN", as an analogue to BCN and other carbonitrides) as a prospective material for future optical applications. This is due to their tunable refractive index that depends on the carbon content. The composites are prepared by introducing alternating pulses of trimethylgallium (TMG) and ammonia (NH 3 ) on silicon substrates to mimic an atomic layer deposition process. Because the GaCN material is hardly reported to the best of our knowledge, a comprehensive characterization is performed to investigate into its chemical nature, primarily to determine whether or not it exists as a single-phase material. It is revealed that GaCN is a composite, consisting of phase-segregated, nanoscale clusters of wurtzitic GaN polycrystals, in addition to inclusions of carbon, nitrogen, and gallium, which are chemically bonded into several forms, but not belonging to the GaN crystals itself. By varying the deposition temperature between 400 and 600 °C and the NH 3 partial pressure between 0.7 × 10 -3 and 7.25 mbar, layers with a wide compositional range of Ga, C, and N are prepared. The role of carbon on the GaCN optical properties is significant: an increase of the refractive index from 2.19 at 1500 nm (for carbon-free polycrystalline GaN) to 2.46 (for GaCN) is achieved by merely 10 at. % of carbon addition. The presence of sp 2 -hybridized C=N clusters and carbon at the interface of the GaN polycrystals are proposed to determine their optical properties. Furthermore, the formation of the GaN polycrystals in the composite occurs through a TMG:NH 3 surface-adduct assisted pathway, whereas the inclusions of carbon, nitrogen, and gallium are formed by the thermal decomposition of the chemisorbed TMG species.

    Original languageEnglish
    Pages (from-to)29567-29576
    Number of pages10
    JournalJournal of physical chemistry C
    Volume122
    Issue number51
    DOIs
    Publication statusPublished - 27 Dec 2018

    Fingerprint

    Refractive index
    Carbon
    refractivity
    composite materials
    carbon
    Composite materials
    Polycrystals
    polycrystals
    Gallium
    gallium
    Nitrogen
    Optical properties
    inclusions
    optical properties
    nitrogen
    Carbon nitride
    Atomic layer deposition
    Composite films
    Silicon
    atomic layer epitaxy

    Cite this

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    title = "Composite GaN-C-Ga ({"}GaCN{"}) Layers with Tunable Refractive Index",
    abstract = "This article describes novel composite thin films consisting of GaN, C, and Ga (termed {"}GaCN{"}, as an analogue to BCN and other carbonitrides) as a prospective material for future optical applications. This is due to their tunable refractive index that depends on the carbon content. The composites are prepared by introducing alternating pulses of trimethylgallium (TMG) and ammonia (NH 3 ) on silicon substrates to mimic an atomic layer deposition process. Because the GaCN material is hardly reported to the best of our knowledge, a comprehensive characterization is performed to investigate into its chemical nature, primarily to determine whether or not it exists as a single-phase material. It is revealed that GaCN is a composite, consisting of phase-segregated, nanoscale clusters of wurtzitic GaN polycrystals, in addition to inclusions of carbon, nitrogen, and gallium, which are chemically bonded into several forms, but not belonging to the GaN crystals itself. By varying the deposition temperature between 400 and 600 °C and the NH 3 partial pressure between 0.7 × 10 -3 and 7.25 mbar, layers with a wide compositional range of Ga, C, and N are prepared. The role of carbon on the GaCN optical properties is significant: an increase of the refractive index from 2.19 at 1500 nm (for carbon-free polycrystalline GaN) to 2.46 (for GaCN) is achieved by merely 10 at. {\%} of carbon addition. The presence of sp 2 -hybridized C=N clusters and carbon at the interface of the GaN polycrystals are proposed to determine their optical properties. Furthermore, the formation of the GaN polycrystals in the composite occurs through a TMG:NH 3 surface-adduct assisted pathway, whereas the inclusions of carbon, nitrogen, and gallium are formed by the thermal decomposition of the chemisorbed TMG species.",
    author = "Sourish Banerjee and Onnink, {Arnoud J.} and Satadal Dutta and Aarnink, {Antonius A.I.} and Gravesteijn, {Dirk J.} and Kovalgin, {Alexey Y.}",
    year = "2018",
    month = "12",
    day = "27",
    doi = "10.1021/acs.jpcc.8b09142",
    language = "English",
    volume = "122",
    pages = "29567--29576",
    journal = "Journal of physical chemistry C",
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    Composite GaN-C-Ga ("GaCN") Layers with Tunable Refractive Index. / Banerjee, Sourish; Onnink, Arnoud J.; Dutta, Satadal; Aarnink, Antonius A.I.; Gravesteijn, Dirk J.; Kovalgin, Alexey Y.

    In: Journal of physical chemistry C, Vol. 122, No. 51, 27.12.2018, p. 29567-29576.

    Research output: Contribution to journalArticleAcademicpeer-review

    TY - JOUR

    T1 - Composite GaN-C-Ga ("GaCN") Layers with Tunable Refractive Index

    AU - Banerjee, Sourish

    AU - Onnink, Arnoud J.

    AU - Dutta, Satadal

    AU - Aarnink, Antonius A.I.

    AU - Gravesteijn, Dirk J.

    AU - Kovalgin, Alexey Y.

    PY - 2018/12/27

    Y1 - 2018/12/27

    N2 - This article describes novel composite thin films consisting of GaN, C, and Ga (termed "GaCN", as an analogue to BCN and other carbonitrides) as a prospective material for future optical applications. This is due to their tunable refractive index that depends on the carbon content. The composites are prepared by introducing alternating pulses of trimethylgallium (TMG) and ammonia (NH 3 ) on silicon substrates to mimic an atomic layer deposition process. Because the GaCN material is hardly reported to the best of our knowledge, a comprehensive characterization is performed to investigate into its chemical nature, primarily to determine whether or not it exists as a single-phase material. It is revealed that GaCN is a composite, consisting of phase-segregated, nanoscale clusters of wurtzitic GaN polycrystals, in addition to inclusions of carbon, nitrogen, and gallium, which are chemically bonded into several forms, but not belonging to the GaN crystals itself. By varying the deposition temperature between 400 and 600 °C and the NH 3 partial pressure between 0.7 × 10 -3 and 7.25 mbar, layers with a wide compositional range of Ga, C, and N are prepared. The role of carbon on the GaCN optical properties is significant: an increase of the refractive index from 2.19 at 1500 nm (for carbon-free polycrystalline GaN) to 2.46 (for GaCN) is achieved by merely 10 at. % of carbon addition. The presence of sp 2 -hybridized C=N clusters and carbon at the interface of the GaN polycrystals are proposed to determine their optical properties. Furthermore, the formation of the GaN polycrystals in the composite occurs through a TMG:NH 3 surface-adduct assisted pathway, whereas the inclusions of carbon, nitrogen, and gallium are formed by the thermal decomposition of the chemisorbed TMG species.

    AB - This article describes novel composite thin films consisting of GaN, C, and Ga (termed "GaCN", as an analogue to BCN and other carbonitrides) as a prospective material for future optical applications. This is due to their tunable refractive index that depends on the carbon content. The composites are prepared by introducing alternating pulses of trimethylgallium (TMG) and ammonia (NH 3 ) on silicon substrates to mimic an atomic layer deposition process. Because the GaCN material is hardly reported to the best of our knowledge, a comprehensive characterization is performed to investigate into its chemical nature, primarily to determine whether or not it exists as a single-phase material. It is revealed that GaCN is a composite, consisting of phase-segregated, nanoscale clusters of wurtzitic GaN polycrystals, in addition to inclusions of carbon, nitrogen, and gallium, which are chemically bonded into several forms, but not belonging to the GaN crystals itself. By varying the deposition temperature between 400 and 600 °C and the NH 3 partial pressure between 0.7 × 10 -3 and 7.25 mbar, layers with a wide compositional range of Ga, C, and N are prepared. The role of carbon on the GaCN optical properties is significant: an increase of the refractive index from 2.19 at 1500 nm (for carbon-free polycrystalline GaN) to 2.46 (for GaCN) is achieved by merely 10 at. % of carbon addition. The presence of sp 2 -hybridized C=N clusters and carbon at the interface of the GaN polycrystals are proposed to determine their optical properties. Furthermore, the formation of the GaN polycrystals in the composite occurs through a TMG:NH 3 surface-adduct assisted pathway, whereas the inclusions of carbon, nitrogen, and gallium are formed by the thermal decomposition of the chemisorbed TMG species.

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    U2 - 10.1021/acs.jpcc.8b09142

    DO - 10.1021/acs.jpcc.8b09142

    M3 - Article

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    VL - 122

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    JO - Journal of physical chemistry C

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