Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet.
Synthesis of highly transparent ultrananocrystalline diamond films from a low-pressure, low-temperature focused microwave plasma jet.
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DOI：
10.1186/1556-276x-7-82
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发表时间：
2012-01-19
影响因子：
--
通讯作者：
Lin CR
中科院分区：
文献类型：
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作者：
Liao WH;Wei DH;Lin CR
本文描述了一种新的低温工艺，即采用Ar-1%CH4-10%H2气体化学反应，通过低压和不加热的微波等离子体射流增强化学气相沉积来合成高度透明的超纳米金刚石[UNCD]薄膜。独特的低压/低温[LPLT]等离子体射流增强生长，甚至与添加的H2和未加热的基板产生UNCD膜类似的那些制备的等离子体增强生长没有添加H2和加热过程。这是由于聚焦等离子体射流有效地补偿了与LPLT生长相关的缓慢动力学。系统地研究了微波等离子体射流合成UNCD薄膜过程中压力的影响。结果表明，随着气压的降低，衬底温度、晶粒尺寸、表面粗糙度和薄膜中sp3碳含量均降低。这是由于随着压力的降低，平均自由程增大，Hα发射大大减少，从而降低了sp2碳相的刻蚀。我们已经证明，从纳米晶（80 nm）到超纳米晶（3至5 nm）金刚石薄膜生长通过微波Ar-1%CH 4 - 10%H 2等离子体射流可以通过改变压力从100到30托控制。使用独特的LPLT（30 Torr/460°C）微波等离子体射流在玻璃基底（玻璃化转变温度[Tg] 557°C）上合成250 nm厚的UNCD膜，其产生具有高sp3碳含量（95.65%）并提供高光学透射率（在700 nm下约86%）的UNCD膜。
This paper describes a new low-temperature process underlying the synthesis of highly transparent ultrananocrystalline diamond [UNCD] films by low-pressure and unheated microwave plasma jet-enhanced chemical vapor deposition with Ar-1%CH4-10%H2 gas chemistry. The unique low-pressure/low-temperature [LPLT] plasma jet-enhanced growth even with added H2 and unheated substrates yields UNCD films similar to those prepared by plasma-enhanced growth without addition of H2 and heating procedure. This is due to the focused plasma jet which effectively compensated for the sluggish kinetics associated with LPLT growth. The effects of pressure on UNCD film synthesis from the microwave plasma jet were systematically investigated. The results indicated that the substrate temperature, grain size, surface roughness, and sp3 carbon content in the films decreased with decreasing pressure. The reason is due to the great reduction of Hα emission to lower the etching of sp2 carbon phase, resulting from the increase of mean free path with decreasing pressure. We have demonstrated that the transition from nanocrystalline (80 nm) to ultrananocrystalline (3 to 5 nm) diamond films grown via microwave Ar-1%CH4-10%H2 plasma jets could be controlled by changing the pressure from 100 to 30 Torr. The 250-nm-thick UNCD film was synthesized on glass substrates (glass transition temperature [Tg] 557°C) using the unique LPLT (30 Torr/460°C) microwave plasma jet, which produced UNCD films with a high sp3 carbon content (95.65%) and offered high optical transmittance (approximately 86% at 700 nm).