꿈의 신소재 '그래핀' 고품질로 여러 층 쌓는 합성법 개발

IBS·삼성종기원 "반도체 고집적 전극 등에 활용"

구리-실리콘 합금 기판을 통한 다층 그래핀 성장 모식도

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(대전=연합뉴스) 박주영 기자 = 기초과학연구원(IBS)은 나노구조물리연구단 이영희 단장과 삼성종합기술원, 부산대 공동 연구팀이 고품질의 4층 짜리 그래핀을 합성하는 데 성공했다고 28일 밝혔다.

그래핀은 흑연의 한 층에서 떼어낸 2차원 물질로, 전기·화학적 특성이 우수해 반도체 분야 '꿈의 신소재'로 불린다.

하지만 밴드갭(전자의 에너지 차이)이 없어 반도체 소재로 활용하기 어렵다.

그래핀을 여러 층으로 쌓으면 집적 회로를 소형화할 수 있고 밴드갭도 조절할 수 있다.

연구팀은 처음으로 고품질의 다층 그래핀을 단결정으로 성장시키는 합성법을 개발했다.

4층 짜리 그래핀의 전자현미경 사진

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단결정은 구성 원자의 배열과 배향이 규칙적인 형태로 다결정보다 열·전기 전도도 등이 우수하다.

화학기상증착법(CVD)을 이용해 다층 그래핀을 합성하기 위한 다양한 시도가 있었지만, 품질을 균일하게 성장시키기 어려웠다.

화학기상증착법은 금속 박막 기판 위에 메탄 등 기체를 주입, 기판을 촉매로 해 그래핀 박막을 성장시키는 방법이다.

기체 상태의 원료가 금속 기판을 만나 분해되고, 분해된 탄소들이 다시 결합하면서 그래핀이 만들어지는 원리이다.

연구팀은 우선 구리-실리콘 합금 기판을 만든 뒤 메탄 가스를 주입, 메탄의 탄소 원자와 실리콘 원자가 구리 표면에 균일한 '실리콘-탄소' 층을 만들도록 했다.

이를 통해 구리-실리콘 합금의 탄소 용해도를 높임으로써 균일한 4층의 그래핀을 합성했다.

메탄 농도에 따라 층수 조절도 가능하다고 연구팀은 설명했다.

이영희 단장은 "대면적의 고품질 그래핀을 4층까지 합성한 연구는 이번이 처음"이라며 "구리 전극을 대체할 반도체 고집적 전극 등으로 활용할 수 있을 것"이라고 말했다.

이번 연구 결과는 국제 학술지 '네이처 나노테크놀로지'(Nature Nanotechnology) 이날 자에 실렸다.

jyoung@yna.co.kr

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