Modifying argon glow discharges by hydrogen addition: effects on analytical characteristics of optical emission and mass spectrometry detection modes

Abstract

An overview of the effects produced by the presence of hydrogen in a glow discharge (GD), generated either in argon or in neon, is given. Extensive work related to the addition of hydrogen to GDs, coupled with optical emission spectrometry (OES) and mass spectrometry (MS), has been published in the last few years in an attempt to explain the processes involved in the discharge of mixed gases. Although numerous experimental results have already been explained theoretically, a complete understanding of the effects brought about by mixing hydrogen with argon (or another discharge inert gas) has not been reported yet. The use of theoretical models implemented using a computer has allowed the importance of some collisional and radiative processes in the inert gas plasma when hydrogen is present to be evaluated. This review shows, however, that both experimental work and theoretical work are still needed. The influence of small quantities of hydrogen on discharge parameters, such as electrical current or dc bias voltage, on crater shapes and on sputtering rates is thoroughly reviewed along with the effect on the analytical signals measured by OES and MS. Also, hydrogen-effect corrections needed to carry out proper calibrations for direct solid quantitative analyses are discussed.

Detection of negative ions in glow discharge mass spectrometry for analysis of solid specimens

“…The possible explanation may be associated with the presence of relatively intense hydrogen peak near the anodic film/tantalum interface. Hydrogen may affect significantly glow discharge parameters, with consequent change of line intensities, sputtering rates, and discharge currents [25,26]. The change of sputtering rate near the interface may correspondingly reduce the accuracy of measurements, with consequent difference when compared with SIMS data.…”

Oxygen reduction by plasma cleaning in low-energy ion implantation of silver ions in titanium

“…O efeito sputtering ocorre em plasma de gases com alto peso molecular, como o argônio que além desta característicá e um gás inerte e de baixo custo [17], [18]. O sputtering ocorre pela transferência de momento deátomos de gás argônio para a superfície do material, onde espécies contaminantes são ejetadas para o plasma [16].…”

“…O efeito etchingé observado em plasma com gases reativos, como o hidrogênio, onde as espécies do plasma formam ligações químicas com espécies contaminantes formando grupos voláteis que são dispersos para o plasma [17], [18].…”

“…Estes dois processos podem ocorrer de forma simultânea fazendo com que a limpeza seja mais rápida, o que viabiliza a técnica para ser utilizada industrialmente [17], [18]. Além disso, outras vantagens devem ser evidenciadas: custo e consumo baixos, podendo ser aplicada a metais, cerâmicas e polímeros.…”

Depth Profile Analysis of Amorphous Silicon Thin Film Solar Cells by Pulsed Radiofrequency Glow Discharge Time of Flight Mass Spectrometry

“…In particular, rf-PGD-OES has been recently investigated in our group for depth profiling analysis of a-Si:H TFSCs [17]. In this context, it should be stressed that the presence of hydrogen in a-Si:H thin films could represent a challenge for quantitative analysis because of the so-called "hydrogen effect": it has been previously reported that the addition of hydrogen to Ar GD could affect the intensity of the analytes and reduces the sputtering rate [18,19]. We have reported that molecular hydrogen added to the discharge gas seems to play a more critical role than the endogenous hydrogen present in the sample itself (e.g., for samples with hydrogen content in the order of 10% atomic) [20,21].…”