Study of phase transition in mocvd grown ga2 o3 from κ to β phase by ex situ and in situ annealing

Junhee Lee; Honghyuk Kim; Lakshay Gautam; Kun He; Xiaobing Hu; Vinayak P. Dravid; Manijeh Razeghi

doi:10.3390/photonics8010017

Study of phase transition in mocvd grown ga₂ o₃ from κ to β phase by ex situ and in situ annealing

Junhee Lee, Honghyuk Kim, Lakshay Gautam, Kun He, Xiaobing Hu, Vinayak P. Dravid, Manijeh Razeghi^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

We report the post-growth thermal annealing and the subsequent phase transition of Ga₂ O₃ grown on c-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). We demonstrated the post-growth thermal annealing at temperatures higher than 900^◦ C under N₂ ambience, by either in situ or ex situ thermal annealing, can induce phase transition from nominally metastable κ-to thermodynamically stable β-phase. This was analyzed by structural characterizations such as high-resolution scanning transmission electron microscopy and x-ray diffraction. The highly resistive as-grown Ga₂ O₃ epitaxial layer becomes conductive after annealing at 1000^◦ C. Furthermore, we demonstrate that in situ annealing can lead to a crack-free β-Ga₂ O₃.

Original language	English (US)
Article number	17
Pages (from-to)	1-8
Number of pages	8
Journal	Photonics
Volume	8
Issue number	1
DOIs	https://doi.org/10.3390/photonics8010017
State	Published - Jan 2021

Keywords

Ga O
MOCVD
Phase transition
Thermal annealing
Thin films

ASJC Scopus subject areas

Atomic and Molecular Physics, and Optics
Instrumentation
Radiology Nuclear Medicine and imaging

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10.3390/photonics8010017

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title = "Study of phase transition in mocvd grown ga2 o3 from κ to β phase by ex situ and in situ annealing",

abstract = "We report the post-growth thermal annealing and the subsequent phase transition of Ga2 O3 grown on c-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). We demonstrated the post-growth thermal annealing at temperatures higher than 900◦ C under N2 ambience, by either in situ or ex situ thermal annealing, can induce phase transition from nominally metastable κ-to thermodynamically stable β-phase. This was analyzed by structural characterizations such as high-resolution scanning transmission electron microscopy and x-ray diffraction. The highly resistive as-grown Ga2 O3 epitaxial layer becomes conductive after annealing at 1000◦ C. Furthermore, we demonstrate that in situ annealing can lead to a crack-free β-Ga2 O3.",

keywords = "Ga O, MOCVD, Phase transition, Thermal annealing, Thin films",

author = "Junhee Lee and Honghyuk Kim and Lakshay Gautam and Kun He and Xiaobing Hu and Dravid, {Vinayak P.} and Manijeh Razeghi",

note = "Funding Information: Acknowledgments: This work is supported by Air Force under agreement of FA9550-19-1-0410. The authors would like to acknowledge the support and interest of Ali Sayir of USAF-AFMC AFMCAFOSR/RTB) and John Belevins (DCIVUSAF AFMC AFRL/RXME) for providing Ga2O3 substrate. The (S)TEM characterizations made use of the EPIC facility of Northwestern University{\textquoteright}s NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern{\textquoteright}s MRSEC program (NSF DMR-1720139). Funding Information: Funding: This work is supported by Air Force under agreement of FA9550-19-1-0410. Funding Information: This work is supported by Air Force under agreement of FA9550-19-1-0410. Publisher Copyright: {\textcopyright} 2021 by the authors. Licensee MDPI, Basel, Switzerland.",

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doi = "10.3390/photonics8010017",

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AU - Lee, Junhee

AU - Kim, Honghyuk

AU - Gautam, Lakshay

AU - He, Kun

AU - Hu, Xiaobing

AU - Dravid, Vinayak P.

AU - Razeghi, Manijeh

N1 - Funding Information: Acknowledgments: This work is supported by Air Force under agreement of FA9550-19-1-0410. The authors would like to acknowledge the support and interest of Ali Sayir of USAF-AFMC AFMCAFOSR/RTB) and John Belevins (DCIVUSAF AFMC AFRL/RXME) for providing Ga2O3 substrate. The (S)TEM characterizations made use of the EPIC facility of Northwestern University’s NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern’s MRSEC program (NSF DMR-1720139). Funding Information: Funding: This work is supported by Air Force under agreement of FA9550-19-1-0410. Funding Information: This work is supported by Air Force under agreement of FA9550-19-1-0410. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

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N2 - We report the post-growth thermal annealing and the subsequent phase transition of Ga2 O3 grown on c-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). We demonstrated the post-growth thermal annealing at temperatures higher than 900◦ C under N2 ambience, by either in situ or ex situ thermal annealing, can induce phase transition from nominally metastable κ-to thermodynamically stable β-phase. This was analyzed by structural characterizations such as high-resolution scanning transmission electron microscopy and x-ray diffraction. The highly resistive as-grown Ga2 O3 epitaxial layer becomes conductive after annealing at 1000◦ C. Furthermore, we demonstrate that in situ annealing can lead to a crack-free β-Ga2 O3.

AB - We report the post-growth thermal annealing and the subsequent phase transition of Ga2 O3 grown on c-plane sapphire substrates by metal organic chemical vapor deposition (MOCVD). We demonstrated the post-growth thermal annealing at temperatures higher than 900◦ C under N2 ambience, by either in situ or ex situ thermal annealing, can induce phase transition from nominally metastable κ-to thermodynamically stable β-phase. This was analyzed by structural characterizations such as high-resolution scanning transmission electron microscopy and x-ray diffraction. The highly resistive as-grown Ga2 O3 epitaxial layer becomes conductive after annealing at 1000◦ C. Furthermore, we demonstrate that in situ annealing can lead to a crack-free β-Ga2 O3.

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KW - MOCVD

KW - Phase transition

KW - Thermal annealing

KW - Thin films

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