Hydrogen loss and its improved retention in hydrogen plasma treated a-SiNx:H films: ERDA study with 100 MeV Ag7+ ions

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

卷:423

Article

Bommali, R. K.¹  Ghosh, S.²  Khan, S. A.³  Srivastava, P.² 

[1] Inst Phys Bhubaneswar, Sachivalya Marg, Bhubaneswar 751005, Odisha, India

[2] Indian Inst Technol Delhi, Dept Phys, Nanostech Lab, New Delhi 110016, India

[3] Interuniv Accelerator Ctr IUAC, Div Mat Sci, Aruna Asaf Ali Marg, New Delhi 110067, India

关键词: Hydrogen out-diffusion;    Amorphous hydrogenated silicon nitride;    Swift heavy ion irradiation;    ERDA;   

DOI  :  10.1016/j.nimb.2018.03.005

来源: Elsevier

【 摘 要 】

Hydrogen loss from a-SiNx:H films under irradiation with 100 MeV Ag7+ ions using elastic recoil detection analysis (ERDA) experiment is reported. The results are explained under the basic assumptions of the molecular recombination model. The ERDA hydrogen concentration profiles are composed of two distinct hydrogen desorption processes, limited by rapid molecular diffusion in the initial stages of irradiation, and as the fluence progresses a slow process limited by diffusion of atomic hydrogen takes over. Which of the aforesaid processes dominates, is determined by the continuously evolving Hydrogen concentration within the films. The first process dominates when the H content is high, and as the H concentration falls below a certain threshold (H-critical) the irradiation generated H radicals have to diffuse through larger distances before recombining to form H-2, thereby significantly bringing down the hydrogen evolution rate. The ERDA measurements were also carried out for films treated with low temperature (300 degrees C) hydrogen plasma annealing (HPA). The HPA treated films show a clear increase in H-critical value, thus indicating an improved diffusion of atomic hydrogen, resulting from healing of weak bonds and passivation of dangling bonds. Further, upon HPA films show a significantly higher H concentration relative to the as-deposited films, at advanced fluences. These results indicate the potential of HPA towards improved H retention in ct-SiNx:H films. The study distinguishes clearly the presence of two diffusion processes in a-SiNx:H whose diffusion rates differ by an order of magnitude, with atomic hydrogen not being able to diffuse further beyond similar to 1 nm from the point of its creation.

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