An electron spectroscopy study of a‐C:H under thermal annealing

Abstract

The structural changes brought about in hydrogenated amorphous carbon (a-C : H) by thermal annealing are investigated by photon-induced electron spectroscopy. The material is found to be stable up to T = 100°C. From 100 to 400°C, H effusion is associated with sp 3 to sp 2 conversion, as revealed by the evolution of the valence states. From 400 to 700°C, the sp 2 sites gather into clusters of increasing size, as revealed by the decreasing binding energy (BE) and increasing asymmetry of the C 1s spectrum.

Thermally induced evolution of hydrogenated amorphous carbon

“…10 The presence of hydrogen in amorphous carbon reduces the thermal stability. 8 Although the basic processes governing the temperature-induced modifications in hydrogenated amorphous carbon (a-C:H), namely, the evolution of hydrogen followed by formation of sp 2 -hybridized carbon, have already been identified, 8,11 no previous studies presented a quantitative evaluation of the energetics of this process. Such studies are challenging for thin films since several techniques that can measure carbon hybridization, such as Raman or nuclear magnetic resonance spectroscopy, are bulk techniques.…”