Heat Treatment of Carbonized Photoresist Mask with Ammonia for Epitaxial Lateral Overgrowth of a-plane GaN on R-plane Sapphire

서지정보

ㆍ발행기관 : 한국재료학회 ㆍ수록지정보 : 한국재료학회지 / 28권 / 4호
ㆍ저자명 : Dae-sik Kim, Jun-hyuck Kwon, Junggeun Jhin, Dongjin Byun

목차

Abstract
1. Introduction
2. Experimental
3. Results and Discussion
4. Conclusion
References

영어 초록

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℃ after carbonization by the pyrolysis in ambient H2 at 1100℃. 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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