| 학회 | 한국재료학회 |
| 학술대회 | 2014년 가을 (11/27 ~ 11/28, 대전컨벤션센터) |
| 권호 | 20권 2호 |
| 발표분야 | B. 나노 재료(Nanomaterials) |
| 제목 | 그래핀 표면에서 원자층 증착 하프늄 산화물의 핵형성과 성장 |
| 초록 | Since graphene is an ideal 2-D conductor, deposition of a dielectric layer is required to fabricate graphene devices. Atomic layer deposition (ALD) is a thin film deposition method that employs surface self-saturated reaction of precursors. Because ALD produces dense films without significant damages, it is suitable to deposit dielectric layers on graphene. On ideal graphene surface, it is hard to deposit a film by ALD since there is no chemically active bonding to initiate ALD nucleation. However, several reports on graphene device fabrications using chemical vapor deposited (CVD) graphene showed continuous ALD film growth. In other reports, ALD layer does not nucleate on graphene surface or island growth occurs. This discrepancy may be caused from non-ideal surface properties of graphene which depend on synthesis process and reaction chemistry of precursors and graphene. Although ALD has been utilized to deposit high-k films to fabricate graphene devices several times, there was no systematic study on surface reactions between ALD precursors and graphene. In this research, we investigated growth characteristics of HfO2 on exfoliated and CVD graphene by using two Hf precursors of tetrakis(dimethylamino)hafnium (TDMAH) and Hafnium tetrachloride (HfCl4). On exfoliated graphene, no growth was observed on basal planes while growth of HfO2 was detected only at the edge of graphene when HfCl4 was used as a precursor. On the contrary, HfO2 nucleated cross CVD graphene at initial growth, then, 75 % of surface coverage was obtained at 90 cycles. Compared to HfCl4, HfO2 ALD by TDMAH on CVD graphene showed unfavorable nucleation and growth with 34% of surface coverage at 90 cycles. Activation energy and surface reaction path were investigated by quantum chemical calculations. Experimental results were discussed with theoretical calculation results. Dielectric properties of ALD HfO2 layer integrated with graphene devices were evaluated for potential applications. It should be noted that this comparative research with experimental and theoretical results will be fundamentally and practically useful for fabrication of graphene based electronic devices. |
| 저자 | 오일권1, 김강식2, 이미진2, 이종훈2, Clement Lansalot-Matras3, 노원태3, Jukka Tanskanen4, 김형준5, 이한보람1 |
| 소속 | 1연세대, 2울산대, 3Air Liquide Korea, 4Department of Chemistry, 5Univ. of Eastern Finland |
| 키워드 | 그래핀; 원자층 증착법; 하프늄 산화물 |
