Ultrafast Deposition of Diamond by Plasma-Enhanced CVD

Theoretical and experimental aspects of non-equilibrium plasmas in different regimes: fundamentals and selected applications

“…36 Variation of the growth rate (in µm/h) as a function of the H-atom density into the plasma bulk according to calculation and measurements we can deduce that a linear relationship links the CH 3 density to the maximum of H-atom density into the gas phase (Fig. 34) [189].…”

“…Growing diamond in a plasma is based on the fact that instead of high temperature high pressure (HPHT) process that occurs, as growth in mines, in the thermodynamic stability of carbon, plasma growth is driven by a kinetics-controlled process [189][190][191][192][193]. As a matter of fact, condensation processes of both graphite and diamond and etching processes of both graphite and diamond are occurring simultaneously.…”

“…To estimate the best way to improve growth rates, one must identify not only how and where H atoms and CH 3 radicals are produced into the gas phase, but also how they can be lost in the gas phase and how they are transported towards the diamond surface [189]. Then, the capability in increasing the H-atom and CH 3radical densities (or fluxes) at the surface proceeds from the understanding of the chemical processes occurring into the plasma and at the plasma-surface interface, both locations constitute the engine of production of the right species.…”

Rapid Growth of Single Crystal Diamond at High Energy Density by Plasma Focusing

“…17.04 cm 3 , 能量密度为 205.4 W/cm 3 ; 而采用聚集装 置条件的等离子体有效体积为 4.41 cm 3 , 能量密度 达到 793.7 W/cm 3 , 是普通钼片条件下的 3.9 倍。由 于二者的微波功率相同, 也可以认为采用聚集装置 的等离子体有效体积是普通钼片的 0.26 倍。这表 明在能量密度提升的同时, 也会牺牲有效的生长 面积。 本研究还测定了从初始参数(900 W, 5 kPa)升至 目标参数(3500 W, 18 kPa)过程中的等离子体发射光 谱变化, 并选取 H α (656 nm)谱线作为参考, 得到了 两种形式下的等离子体核心原子氢变化曲线(如图 3 所示)。 原子氢在 MPCVD 单晶金刚石生长中发挥了 至关重要的作用, 其不仅直接参与金刚石生长过程, 还参与了甲基基团的产生, 并能够抑制非金刚石相 的生成, 所以原子氢的浓度是影响金刚石生长速率 和品质的重要因素之一[21] 。对比图 3 中的两条曲线 可以看出, 两种形式下等离子体核心原子氢浓度都 随参数增大而不断提高, 但聚集装置条件下的等离 图 1 3500 W, 18 kPa 条件下舱体内电场强度和电子密度的分布情况仿真结果 Fig. 1 Simulation results of the distribution of electric field and electron density in the reaction chamber at 3500 W and 18 kPa (a) Electric field distribution with molybdenum disk; (b) Electric field distribution with focusing structure; (c) Electron density distribution with molybdenum disk; (d) Electron density distribution with focusing structure 图 2 两种条件下等离子体的实际观测图(微波功率 3500 W, 舱体气压 18 kPa, 加装 H α 滤镜) Fig.…”