偏压技术在金刚石薄膜制备中应用的进展

近年来，用偏压技术进行异质外延单晶金刚石生长并将其尺寸增大到英寸级以上。偏压技术强大的形核能力使其也可用于制备取向金刚石薄膜、纳米金刚石薄膜和超纳米金刚石薄膜。本文综述了国内外关于偏压技术的机理以及偏压的形式和设备等方面的研究现状，以及表面反应模型、热尖峰模型和亚层注入模型的机理。常用的偏压包括直流偏压、直流脉冲偏压、脉冲叠合偏压和双极性脉冲偏压。还介绍了偏压对金刚石薄膜组织和性能的影响，详细阐述了其对取向生长，二次形核率，无定形碳-石墨-金刚石相转变以及生长速率和结合力的作用规律和机理。加偏压能改变轰击粒子能量和特定基团的浓度、影响金刚石相的转变和晶粒取向和尺寸，进而影响金刚石薄膜的光，力，热，电学性能。还讨论了目前研究工作中存在的一些不足，如偏压作用的机理仍不清晰，对电子浓度变化，氢原子刻蚀的作用尚缺少明确的解释等。最后展望了偏压技术在金刚石制备领域未来的研究和应用方向。

Progress on Application of Bias Technology for Preparation of Diamond Films

In recent years, heteroepitaxial monocrystalline diamond has been grown by bias voltage technique and its size has been increased to over inch level. Since the application of bias can act as a means to significantly promote nuclear capability of diamound, therefore, the bias voltage technology may be used to prepare oriented diamond films, nano diamond films and ultra-nano diamond films etc. In this paper, the mechanism related with the action of bias technology, the forms and devices of bias technology, as well as the mechanism of surface reaction model, thermal peak model and sublayer injection model are reviewed. The commonly used bias techniques include DC bias, DC pulse bias, pulse overlap bias and bipolar pulse bias. The effect of bias voltage on the microstructure and properties of diamond films are also introduced, and the effect of applied bias voltage on the orientation growth, secondary nucleation rate, amorphous carbon-graphite-diamond phase transition, growth rate and bonding force of diamond films are described in detail. Biasing can change the energy of bombarded particles and the concentration of specific groups, affect the transformation of diamond phase and grain orientation and size, and then affect the optical, mechanical, thermal and electrical properties of diamond films. Some shortcomings in the present research work are also discussed, such as the mechanism related with the action of bias is still not clear, the change of electron concentration and the effect of hydrogen etching are still not clearly explained. Finally, the future research and application directions of bias voltage technology for diamond preparation are also prospected.