Experimental and modeling studies of B atom number density distributions in hot filament activated B2H6/H2 and B2H6/CH4/H2 gas mixtures
Experimental and modeling studies of B atom number density distributions in hot filament activated B2H6/H2 and B2H6/CH4/H2 gas mixtures
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DOI：
10.1021/jp053455p
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发表时间：
2006-03-09
影响因子：
2.9
通讯作者：
Mankelevich, YA
中科院分区：
文献类型：
--
作者：
Comerford, DW;Cheesman, A;Mankelevich, YA
本文报道了发生在稀热灯丝（HF）活化的B2H6/H-2和B2H6/CH4/H-2气体混合物中的气相化学实验和模型研究。利用共振增强多光子电离方法测量了B（和H）原子的空间分辨相对数密度，它与工艺条件（如HF材料及其温度、B2H6/H2混合比和CH4的存在与否）有关。利用简化的气相化学表示，对这种HF活性气体混合物中普遍存在的H/B化学进行三维建模，成功地再现了所有实验观察到的趋势，并说明了“H移”反应BHx + H可逆箭头BHx-1 + H-2 （x = 1-3）在实现各种BHx （x = 0-3）之间快速相互转化中的关键作用。在适宜于化学气相沉积法生长掺硼金刚石的分压下，CH4的加入导致在HF附近测量到的B原子信号降低了30%。该模型表明，这主要是由于HF附近伴随的H原子耗竭，但它也允许我们首次评估在CH4加入HF活化的B2H6/H-2气体混合物时B/C偶联反应的可能贡献。
Experimental and modeling studies of the gas-phase chemistry occurring in dilute, hot filament (HF) activated B2H6/H-2 and B2H6/CH4/H-2 gas mixtures are reported. Spatially resolved relative number densities of B (and H) atoms have been measured by resonance enhanced multiphoton ionization methods, as a function of process conditions (e.g. the HF material and its temperature, the B2H6/H2 mixing ratio, and the presence (or not) of added CH4). Three-dimensional modeling of the H/B chemistry prevailing in such HF activated gas mixtures using a simplified representation of the gas phase chemistry succeeds in reproducing all of the experimentally observed trends, and in illustrating the key role of the "H-shifting" reactions BHx + H reversible arrow BHx-1 + H-2 (x = 1-3) in enabling rapid interconversion between the various BHx (x = 0-3) species. CH4 addition, at partial pressures appropriate for growth of boron-doped diamond by chemical vapor deposition methods, leads to similar to 30% reduction in the measured B atom signal near the HF. The modeling suggests that this is mainly due to concomitant H atom depletion near the HF, but it also allows us a first assessment of the possible contributions from B/C coupling reactions upon CH4 addition to HF activated B2H6/H-2 gas mixtures.