介质阻挡放电氢等离子体中氢原子浓度的光谱诊断

Spectroscopic Measurements of Atomic Hydrogen Concentrations in Dielectric Barrier Discharge Hydrogen Plasmas

在化学气相沉积功能材料等离子体刻蚀及表面处理等过程中,氢原子起着非常重要的作用。文章详细论述了利用发射光谱技术诊断氢原子的基本原理,以氩气作为内标对介质阻挡放电氢等离子体中的氢原子浓度进行了定量的诊断,研究了氢原子浓度、氢分子解离率随气压的变化规律。发现在0.32到5.1kPa气压范围内,氢分子的解离率由5.2%下降到0.089%,相应的氢原子浓度由4.9×1015.cm-3下降到1.3×1015.cm-3。文章还研究了氢Balmer系以及氩(750.4nm)谱线的发射强度随气压、放电电压、频率等放电参数的变化规律。

Atomic hydrogen plays important roles in chemical vapor deposition of functional materials, plasma etching, and surface cleaning. The present work introduces the fundamental principle to determine atomic hydrogen density via optical emission spectroscopy using Ar as an actinometer, and also reports the experimental results of atomic hydrogen density in the DBD discharge hydrogen plasmas. The variations of atomic hydrogen density and the hydrogen dissociation fraction as a function of pressure were calculated based on some of the available electron-impact excitation cross section and quenching cross sections in the literatures. In this work, as the pressure increases from 0.32 to 5. 1 kPa, the hydrogen dissociation fraction decreases from 5.2% to 0. 089%, and the atomic hydrogen density decreases from 4.9×10^15 cm^-3 to 1.3×10^15 cm^-3. The variations of H atom Balmer lines and Ar（750. 4 nm） emission intensity as functions of gas pressure, discharge voltage, and frequency were also investigated.