The interplay of surface processes and negative ions in radio-frequency driven oxygen and hydrogen plasmas

Surface interactions and negative ions play key roles in the properties of reactive molecular processing plasmas. Radio-frequency driven oxygen and hydrogen plasmas are ideal test-beds for investigations into the role of surface interactions for the chemical kinetics of the plasma and associated negative ion formation. Oxygen containing plasmas can exhibit either mostly electro-negative or mostly electro-positive characters [1, 2]. Oxygen negative ions can be efficiently destroyed by singlet oxygen which in turn is itself strongly influenced by surface reactions and surface properties [3]. Atomic oxygen, as a key reactive species, can also be dependent on surface properties [4]. In hydrogen plasmas, negative ions can be produced through surface processes as well as volume processes [5]. Nitrogen doped diamond surfaces are promising candidates for enhanced surface production of negative hydrogen ions [6,7]. Volume processes are determined by dissociative attachment involving vibrationally exited hydrogen molecules. These in turn are also dependent on surface properties [5]. This interplay between surface properties and the plasma chemical kinetics as well as plasma dynamics will be discussed for the examples of single [1,3,4,5,6,7] and multi-frequency [2,8,9] driven oxygen and hydrogen plasmas.

Related references

[1] A Greb et al., APL 103 (24), 244101 (2013)

[2] AR Gibson et al., APL 106 (5), 054102 (2015)

[3] A Greb et al., PSST 24 (4), 044003 (2015)

[4] T Tsutsumi et al. JApplPhys 121 (14), 143301 (2017)

[5] J Ellis et al., JPhysD 53 (48), 485202 (2020)

[6] GJ Smith et al., JPhysD 53 (46), 465204 (2020)

[7] GJ Smith et al., JPhysD 54 (43), 435201 (2021)

[8] A Derzsi et al., PSST 26 (3), 034002 (2017)

[9] B Bruneau et al., PSST 25 (1), 01LT02 (2015)