Role of Pressure in the Growth of Hexagonal Boron Nitride Thin Films from Ammonia-Borane

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• 作者：Justin C. Koepke ; Joshua D. Wood ; Yaofeng Chen ; Scott W. Schmucker ; Ximeng Liu ; Noel N. Chang ; Lea Nienhaus ; Jae Won Do ; Enrique A. Carrion ; Jayan Hewaparakrama ; Aniruddh Rangarajan ; Isha Datye ; Rushabh Mehta ; Richard T. Haasch ; Martin Gruebele ; Gregory S. Girolami ; Eric Pop ; Joseph W. Lyding
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：June 28, 2016
• 年：2016
• 卷：28
• 期：12
• 页码：4169-4179
• 全文大小：727K
• 年卷期：0
• ISSN：1520-5002

文摘

We analyze the optical, chemical, and electrical properties of chemical vapor deposition (CVD) grown hexagonal boron nitride (h-BN) using the precursor ammonia-borane (H<sub>3sub>N–BH<sub>3sub>) as a function of Ar/H<sub>2sub> background pressure (P<sub>TOTsub>). Films grown at P<sub>TOTsub> ≤ 2.0 Torr are uniform in thickness, highly crystalline, and consist solely of h-BN. At larger P<sub>TOTsub>, with constant precursor flow, the growth rate increases, but the resulting h-BN is more amorphous, disordered, and sp<sup>3sup>-bonded. We attribute these changes in h-BN grown at high pressure to incomplete thermolysis of the H<sub>3sub>N–BH<sub>3sub> precursor from a passivated Cu catalyst. A similar increase in h-BN growth rate and amorphization is observed even at low P<sub>TOTsub> if the H<sub>3sub>N–BH<sub>3sub> partial pressure is initially greater than the background pressure P<sub>TOTsub> at the beginning of growth. h-BN growth using the H<sub>3sub>N–BH<sub>3sub> precursor reproducibly can give large-area, crystalline h-BN thin films, provided that the total pressure is under 2.0 Torr and the precursor flux is well-controlled.