Optical emission diagnostics of laser-induced plasma for diamond-like film deposition

Chen, X.; Mazumder, Jyoti; Purohit, A.

doi:10.1007/bf00324774

Cited by 57 publications

(40 citation statements)

References 37 publications

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“…The CN violet system has three strong sequences with heads at 421.6, 388.3, and 359 nm ͑the 388.3 head being the strongest͒ 28 which have been observed by other workers. [37][38][39] In our system, the 359 nm band is obscured by the strong N 2 second positive bands but when the 388.3 nm band is well developed, bands associated with the 421.6 nm sequence appear.…”

Section: Resultsmentioning

confidence: 99%

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

Clay

Speakman

Amaratunga

et al. 1996

Journal of Applied Physics

147

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Optical emission spectra ͑OES͒ from CH 4 /N 2 rf plasmas, which are used for the deposition of nitrogen-containing hydrogenated amorphous carbon ͑a-C:H:N͒ thin films, have been characterized. Previously unidentified spectral lines have been assigned to atomic N. Further identified species include CH, H, H 2 , N 2 , N 2 ϩ , N, and CN. Variations between spectra from the pure CH 4 or N 2 plasmas and the mixed CH 4 /N 2 plasma are discussed. The enhancement of excited nitrogen species, with the addition CH 4 , is attributed to Penning ionization. The observed OES variations of the CH 4 /N 2 plasma with power, pressure, and CH 4 /N 2 ratio are explained in terms of possible reaction mechanisms and their activation, and correlated with preliminary film growth characteristics.

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Section: Resultsmentioning

confidence: 99%

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

Clay

Speakman

Amaratunga

et al. 1996

Journal of Applied Physics

147

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“…7 Even though significant advances on DLC films have been achieved in recent years, understanding of the effect of laserproduced plasma on film properties is still lacking. [8][9][10][11][12] Laser plasma plume characterization is essential because it leads to an understanding of the interaction of various species within the plume, thereby opening the possibility of optimizing the properties of the films.…”

Section: Introductionmentioning

confidence: 99%

Effect of laser intensity on the properties of carbon plasmas and deposited films

Ong

Chang

1997

Phys. Rev. B

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The effect of laser intensity on the deposition of diamondlike carbon ͑DLC͒ films has been studied using an ArF ͑193 nm͒ pulsed excimer laser. Our results are found to be distinct from other studies using Nd-YAG infrared or excimer 248-nm lasers. Two issues concerning the growth mechanism of the films are discussed: ͑1͒ the dynamics of the laser-induced plasma and ͑2͒ the dependence of the nature of the deposited films on laser intensity. To address the first issue, time-integrated optical emission spectroscopy has been carried out to investigate the carbon plasma induced by the ArF ͑193 nm͒ laser. Instead of molecular carbon bands ͑C 2 ͒, monoatomic neutral ͑C I ͒ and ionic ͑C II ͒ emission lines are found to dominate the spectra. The emissions of ͑C I ͒ and ͑C II ͒ have been studied as a function of laser intensity. For low laser intensity, the laser irradiation removes the target surface material primarily through thermal evaporation. When the laser intensity is above a threshold of ͑3.7-4͒ϫ10 8 W/cm 2 , the evaporated species are also ionized. The observed phenomenon can be attributed to higher multiphoton ionization and inverse bremsstrahlung rate as the laser intensity is increased. For the second issue, films deposited at various intensities have been characterized by ellipsometry. Results show that films deposited at low intensity are found to have excellent optical transparency ͑E g ϭ2.3 eV͒, which implies a considerable amount of sp 3 bonds. However, films deposited at higher intensities are found to be more graphitic. The damage threshold has also been located at 3.7ϫ10 8 W/cm 2 . A qualitative structural analysis based on the effective-medium approximation has been performed on the deposited films to investigate the influence of laser intensity on their microstructures. ͓S0163-1829͑97͒01407-0͔

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“…In order to determine formation mechanisms, we have estimated the vibrational temperature of CN molecules using a relative emission intensity method. Assuming a Boltzmann distribution in the density of excited molecular levels, the emission intensity of vibrational transition (I ν ν ) is related to the vibrational temperature (T vib ) by expression [13]: …”

Section: Resultsmentioning

confidence: 99%

Plasma characterization of pulsed-laser ablation process used for fullerene-like CNx thin film deposition

Riascos¹,

Zambrano²

2004

Braz. J. Phys.

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An in situ Optical Emission Spectroscopy (OES) characterization was performed on Pulsed-Laser Ablation (PLA) process used for fullerene-like CNx thin film deposition at nitrogen pressures within the 5 -100 mTorr range. Plumes were generated by ablation of pyrolytic graphite (99.99%) target using a (500 mJ, 7 ns, 1064 nm) Nd: YAG-pulsed laser. The spectra from the plume show, essentially, the presence of the band heads of CN Violet vibrational/rotational B 2 Σ + -X 2 Σ + system and the characteristic C 2 emission lines, belonging to the Swan A 3 Π g -X '3 Π u system. These excited CN and C 2 molecules were generated by laser ablation and by collisions of the plume with the substrate surface. Their vibrational temperatures were strongly dependent on nitrogen pressure during the deposition process and presented a decrease between 2.64 and 1.23 eV, as pressure increased from 5 to 100 mTorr. Synthesis of fullerene-like structures required high molecular temperatures at the condensation surface. High concentrations of CN radicals in the plasma promoted nitrogen incorporation into the films. The OES plasma characterization allowed for a correlation of the concentration and vibrational temperatures of CN and C2 species present in the plasma with the fullerene-like CNx film composition and bonding, determined by XPS, IR, and Raman spectroscopy.

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Optical emission diagnostics of laser-induced plasma for diamond-like film deposition

Cited by 57 publications

References 37 publications

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

Effect of laser intensity on the properties of carbon plasmas and deposited films

Plasma characterization of pulsed-laser ablation process used for fullerene-like CNx thin film deposition

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