Low Density Supersonic Plasma Jet Synthesis of Thin Films of Refractory and Wide Band-Gap Nitrides

低密度超音速等离子射流合成难熔和宽带隙氮化物薄膜

• 批准号: 9707923
• 负责人: Mark Cappelli
• 金额: $ 24.72万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2001-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9707923&HistoricalAwards=false
• 关键词: Low; Density; Supersonic; Plasma; Jet

Abstract - Cappelli CTS-9707923 This is a combined experimental and modelling study oriented toward an efficient process for the synthesis of advanced materials in the nitride family. A supersonic plasma jet generated by an arc-heated flow and expanded to low densities provides a large flux of energetic dissociated (atomic) nitrogen into which a wide variety of reactants (such as gallium trichloride, aluminum trichloride, methane, or boron trichloride) are injected to generate a reacting flow from which products condence onto a substrate to form films, coatings, or epitaxial layers. The ability to apply a controlled electrical bias to the substrate provides an added variable to influence film structure and properties. The project includes modelling of reactant injection and subsequent decomposition in the plume; modelling of ion transport through the plasma sheath surrounding the substrate; development of empirical heterogeneous models of film growth; measurement of concentratures of critical gas-phase species during film deposition by optical absorption spectroscopy; measurement of concentrations and energies of a broader range of neutral and ionic radicals by molecular-beam mass spectrometry; and correlation of vapor-phase properties to film structure as ascertained by infrared absorption (IR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). Optical and mechanical properties of the deposited films are also measured. This study addresses the synthesis of a number of nitrides that form the basis of "space-age" ceramics. These include cubic boron nitride (c-BN), carbon nitride (C3 N4), gallium nitride (GaN), aluminum nitride (AlN), and the mixed aluminum/gallium nitrides. The unusual mechanical, electrical, and optical properties of these materials make them attractive for many applications, but their wide use is inhibited by the lack of an economic method of s ynthesis.

摘要 - Cappelli CTS-9707923 这是一项实验和建模相结合的研究，旨在建立氮化物家族先进材料的高效合成工艺。 由电弧加热流产生并膨胀至低密度的超音速等离子射流提供大量高能离解（原子）氮，多种反应物（例如三氯化镓、三氯化铝、甲烷或三氯化硼）被注入其中注入以产生反应流，产物在该反应流中凝结到基材上以形成薄膜、涂层或外延层。 向基材施加受控电偏压的能力提供了影响薄膜结构和性能的附加变量。 该项目包括反应物注入和随后羽流分解的建模；通过基材周围的等离子体鞘的离子传输模型；薄膜生长经验异质模型的发展；通过光学吸收光谱法测量薄膜沉积过程中关键气相物质的浓度；通过分子束质谱法测量更广泛的中性和离子自由基的浓度和能量；通过红外吸收 (IR) 光谱、拉曼光谱、X 射线光电子能谱 (XPS)、X 射线衍射 (XRD) 和近边缘 X 射线吸收精细结构确定气相特性与薄膜结构的相关性光谱（NEXAFS）。 还测量了沉积薄膜的光学和机械性能。 这项研究涉及多种氮化物的合成，这些氮化物构成了“太空时代”陶瓷的基础。 这些材料包括立方氮化硼 (c-BN)、氮化碳 (C3 N4)、氮化镓 (GaN)、氮化铝 (AlN) 以及混合铝/氮化镓。 这些材料不寻常的机械、电学和光学特性使它们对许多应用具有吸引力，但由于缺乏经济的合成方法，它们的广泛使用受到限制。