In situ etching of β-Ga2O3 using tert-butyl chloride in an MOCVD system

Cameron A. Gorsak; Henry J. Bowman; Katie R. Gann; Joshua T. Buontempo; Kathleen T. Smith; Pushpanshu Tripathi; Jacob Steele; Debdeep Jena; Darrell G. Schlom; Huili Grace Xing; Michael O. Thompson; Hari P. Nair

doi:10.1063/5.0239152

In situ etching of β-Ga₂O₃ using tert-butyl chloride in an MOCVD system

Cameron A. Gorsak, Henry J. Bowman, Katie R. Gann, Joshua T. Buontempo, Kathleen T. Smith, Pushpanshu Tripathi, Jacob Steele, Debdeep Jena, Darrell G. Schlom, Huili Grace Xing, Michael O. Thompson, Hari P. Nair

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Abstract

In this study, we investigate in situ etching of β-Ga₂O₃ in a metalorganic chemical vapor deposition system using tert-butyl chloride (TBCl). We report etching of both heteroepitaxial 2 ¯ 01 -oriented and homoepitaxial (010)-oriented β-Ga₂O₃ films over a wide range of substrate temperatures, TBCl molar flows, and reactor pressures. We infer that the likely etchant is HCl (g), formed by the pyrolysis of TBCl in the hydrodynamic boundary layer above the substrate. The temperature dependence of the etch rate reveals two distinct regimes characterized by markedly different apparent activation energies. The extracted apparent activation energies suggest that at temperatures below ∼800 °C, the etch rate is likely limited by desorption of etch products. The relative etch rates of heteroepitaxial 2 ¯ 01 and homoepitaxial (010) β-Ga₂O₃ were observed to scale by the ratio of the surface energies, indicating an anisotropic etch. Relatively smooth post-etch surface morphology was achieved by tuning the etching parameters for (010) homoepitaxial films.

Original language	English
Article number	242103
Journal	Applied Physics Letters
Volume	125
Issue number	24
DOIs	https://doi.org/10.1063/5.0239152
State	Published - Dec 9 2024
Externally published	Yes

Funding

We acknowledge support from the AFOSR/AFRL ACCESS Center of Excellence under Award No. FA9550-18-10529. C.A.G. acknowledges support from the National Defense Science and Engineering Graduate (NDSEG) Fellowship. H.J.B. acknowledges support from the National Science Foundation (NSF) [Platform for the Accelerated Realization, Analysis and Discovery of Interface Materials (PARADIM)] under Cooperative Agreement No. DMR-1539918. We also acknowledge support from PARADIM for the use of XRD. Substrate dicing and AFM were performed at the Cornell NanoScale Facility, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the NSF (Grant No. NNCI-2025233).

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@article{23daa8036c3e4dd987c557e95e3e4973,

title = "In situ etching of β-Ga2O3 using tert-butyl chloride in an MOCVD system",

abstract = "In this study, we investigate in situ etching of β-Ga2O3 in a metalorganic chemical vapor deposition system using tert-butyl chloride (TBCl). We report etching of both heteroepitaxial 2 ¯ 01 -oriented and homoepitaxial (010)-oriented β-Ga2O3 films over a wide range of substrate temperatures, TBCl molar flows, and reactor pressures. We infer that the likely etchant is HCl (g), formed by the pyrolysis of TBCl in the hydrodynamic boundary layer above the substrate. The temperature dependence of the etch rate reveals two distinct regimes characterized by markedly different apparent activation energies. The extracted apparent activation energies suggest that at temperatures below ∼800 °C, the etch rate is likely limited by desorption of etch products. The relative etch rates of heteroepitaxial 2 ¯ 01 and homoepitaxial (010) β-Ga2O3 were observed to scale by the ratio of the surface energies, indicating an anisotropic etch. Relatively smooth post-etch surface morphology was achieved by tuning the etching parameters for (010) homoepitaxial films.",

author = "Gorsak, \{Cameron A.\} and Bowman, \{Henry J.\} and Gann, \{Katie R.\} and Buontempo, \{Joshua T.\} and Smith, \{Kathleen T.\} and Pushpanshu Tripathi and Jacob Steele and Debdeep Jena and Schlom, \{Darrell G.\} and Xing, \{Huili Grace\} and Thompson, \{Michael O.\} and Nair, \{Hari P.\}",

note = "Publisher Copyright: {\textcopyright} 2024 Author(s).",

year = "2024",

month = dec,

day = "9",

doi = "10.1063/5.0239152",

language = "English",

volume = "125",

journal = "Applied Physics Letters",

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T1 - In situ etching of β-Ga2O3 using tert-butyl chloride in an MOCVD system

AU - Gorsak, Cameron A.

AU - Bowman, Henry J.

AU - Gann, Katie R.

AU - Buontempo, Joshua T.

AU - Smith, Kathleen T.

AU - Tripathi, Pushpanshu

AU - Steele, Jacob

AU - Jena, Debdeep

AU - Schlom, Darrell G.

AU - Xing, Huili Grace

AU - Thompson, Michael O.

AU - Nair, Hari P.

PY - 2024/12/9

Y1 - 2024/12/9

N2 - In this study, we investigate in situ etching of β-Ga2O3 in a metalorganic chemical vapor deposition system using tert-butyl chloride (TBCl). We report etching of both heteroepitaxial 2 ¯ 01 -oriented and homoepitaxial (010)-oriented β-Ga2O3 films over a wide range of substrate temperatures, TBCl molar flows, and reactor pressures. We infer that the likely etchant is HCl (g), formed by the pyrolysis of TBCl in the hydrodynamic boundary layer above the substrate. The temperature dependence of the etch rate reveals two distinct regimes characterized by markedly different apparent activation energies. The extracted apparent activation energies suggest that at temperatures below ∼800 °C, the etch rate is likely limited by desorption of etch products. The relative etch rates of heteroepitaxial 2 ¯ 01 and homoepitaxial (010) β-Ga2O3 were observed to scale by the ratio of the surface energies, indicating an anisotropic etch. Relatively smooth post-etch surface morphology was achieved by tuning the etching parameters for (010) homoepitaxial films.

AB - In this study, we investigate in situ etching of β-Ga2O3 in a metalorganic chemical vapor deposition system using tert-butyl chloride (TBCl). We report etching of both heteroepitaxial 2 ¯ 01 -oriented and homoepitaxial (010)-oriented β-Ga2O3 films over a wide range of substrate temperatures, TBCl molar flows, and reactor pressures. We infer that the likely etchant is HCl (g), formed by the pyrolysis of TBCl in the hydrodynamic boundary layer above the substrate. The temperature dependence of the etch rate reveals two distinct regimes characterized by markedly different apparent activation energies. The extracted apparent activation energies suggest that at temperatures below ∼800 °C, the etch rate is likely limited by desorption of etch products. The relative etch rates of heteroepitaxial 2 ¯ 01 and homoepitaxial (010) β-Ga2O3 were observed to scale by the ratio of the surface energies, indicating an anisotropic etch. Relatively smooth post-etch surface morphology was achieved by tuning the etching parameters for (010) homoepitaxial films.

UR - https://www.scopus.com/pages/publications/85212052271

U2 - 10.1063/5.0239152

DO - 10.1063/5.0239152

M3 - Article

AN - SCOPUS:85212052271

SN - 0003-6951

VL - 125

JO - Applied Physics Letters

JF - Applied Physics Letters

IS - 24

M1 - 242103

ER -

In situ etching of β-Ga₂O₃ using tert-butyl chloride in an MOCVD system

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