Complete characterization by Raman spectroscopy of the structural properties of thin hydrogenated diamond-like carbon films exposed to rapid thermal annealing

Abstract

Gold nanoparticle formation in diamond-like carbon using two different methods: Gold ion implantation and codeposition of gold and carbon J. Appl. Phys. 112, 074312 (2012) We have demonstrated that multi-wavelength Raman and photoluminescence spectroscopies are sufficient to completely characterize the structural properties of ultra-thin hydrogenated diamondlike carbon (DLC:H) films subjected to rapid thermal annealing (RTA, 1 s up to 659 C) and to resolve the structural differences between films grown by plasma-enhanced chemical vapor deposition, facing target sputtering and filtered cathodic vacuum arc with minute variations in values of mass density, hydrogen content, and sp 3 fraction. In order to distinguish unequivocally between films prepared with different density, thickness, and RTA treatment, a new method for analysis of Raman spectra was invented. This newly developed analysis method consisted of plotting the position of the Raman G band of carbon versus its full width at half maximum. Moreover, we studied the passivation of non-radiative recombination centers during RTA by performing measurements of the increase in photoluminescence in conjunction with the analysis of DLC:H networks simulated by molecular dynamics. The results show that dangling bond passivation is primarily a consequence of thermally-induced sp 2 clustering rather than hydrogen diffusion in the film. V C 2014 AIP Publishing LLC. [http://dx

Advanced spectroscopic analyses on a:C-H materials: Revisiting the EELS characterization and its coupling with multi-wavelength Raman spectroscopy

“…Recently there is a renewed interest for these materials as they exhibits a superlow friction coefficient and long wear life in ultra-high vacuum which makes them one of the most promising solid lubricant coating candidate for aerospace applications [6][7][8][9][10]. The origin of the superlow friction is still under investigation but seems to be closely related to the passivation of the surface by the hydrogen and to the sp 3 to sp 2 rehybridization [8][9][10][11]. The proper characterization of the hydrogen content together with the sp 2 fraction is thus of particular importance.…”

“…The high stability of these materials makes them very suitable for a large range of applications including the use as protecting coatings for data storage devices in order to preserve both magnetic discs and recording heads from corrosion and wear [3][4][5]. Recently there is a renewed interest for these materials as they exhibits a superlow friction coefficient and long wear life in ultra-high vacuum which makes them one of the most promising solid lubricant coating candidate for aerospace applications [6][7][8][9][10].…”

“…Due to the extremely good sensitivity on structural modifications involving sp 2 carbons, Raman spectroscopy analysis has been associated to most of the last studies on a:C-H materials [3,4,17,19,[23][24][25][26][27][28][29][30]. The reason behind this high sensitivity is the resonance phenomena between the laser wavelength excitation used and a local band gap of a given sp 2 cluster in the amorphous carbon.…”

“…The proper characterization of the hydrogen content together with the sp 2 fraction is thus of particular importance. These coatings need also to be thermally stable and changes in a-C:H local chemistry during thermal annealing have then regained an interest these last few years [3,4,[12][13][14][15][16][17][18][19][20][21][22].…”

“…Hydrogenated amorphous carbon (a-C:H) thin films constitute a mix, at the local scale, of sp 2 clusters and sp 3 carbon domains with different contents of H. The physical and chemical properties of these films are strongly governed by on the balance between the sp 2 clustering and H defects [1,2]. The high stability of these materials makes them very suitable for a large range of applications including the use as protecting coatings for data storage devices in order to preserve both magnetic discs and recording heads from corrosion and wear [3][4][5].…”