Heat treatment of Carbonized Photoresist Mask with ammonia for epitaxial lateral overgrowth of a-plane GaN on R-plane sapphire

Dae sik Kim, Jun hyuck Kwon, Junggeun Jhin, Dong Jin Byun

Research output: Contribution to journalArticle

Abstract

Epitaxial (1120) a-plane GaN films were grown on a (1102) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient H2/NH3 mixture gas at 1140 °C after carbonization by the pyrolysis in ambient H2 at 1100°C. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ω-2θ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After Ar+ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.

Original languageEnglish
Pages (from-to)208-213
Number of pages6
JournalKorean Journal of Materials Research
Volume28
Issue number4
DOIs
Publication statusPublished - 2018 Apr 1

Fingerprint

Aluminum Oxide
Photoresists
Ammonia
Sapphire
Masks
Heat treatment
Contamination
Organic Chemicals
Carbon films
Organic chemicals
Carbonization
Chemical vapor deposition
Substrates
Carbon
X ray photoelectron spectroscopy
Metals
Gas mixtures
Lithography
Surface morphology
Etching

Keywords

  • Epitaxial lateral overgrowth
  • Gallium nitride thin film
  • Heat treatment
  • Metal organic chemical vapor deposition
  • Photoresist mask

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Heat treatment of Carbonized Photoresist Mask with ammonia for epitaxial lateral overgrowth of a-plane GaN on R-plane sapphire. / Kim, Dae sik; Kwon, Jun hyuck; Jhin, Junggeun; Byun, Dong Jin.

In: Korean Journal of Materials Research, Vol. 28, No. 4, 01.04.2018, p. 208-213.

Research output: Contribution to journalArticle

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abstract = "Epitaxial (1120) a-plane GaN films were grown on a (1102) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient H2/NH3 mixture gas at 1140 °C after carbonization by the pyrolysis in ambient H2 at 1100°C. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ω-2θ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After Ar+ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.",
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