Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

[PDF] http://dx.doi.org/10.3952/lithjphys.47321

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 47, 343–350 (2007)

MODIFICATION OF AMORPHOUS a-C:H FILMS BY LASER IRRADIATION
A. Grigonis^a, Ž. Rutkūnienė^a, A. Medvid^b, P. Onufrijevs^b, and J. Babonas^c
^aPhysics Department, Kaunas University of Technology, Studentų 50, LT-51368 Kaunas, Lithuania
E-mail: zirut@ktu.lt
^bRiga Technical University, 14 Azenes St., LV-1048 Riga, Latvia
^cSemiconductor Physics Institute, A. Goštauto 11, LT-01108 Vilnius, Lithuania

Received 20 June 2007

Amorphous diamond-like hydrogenated carbon films a-C:H were formed on Si wafers by a direct ion beam deposition method from acetylene or a gas mixture of acetylene and hydrogen. The samples were irradiated in a scanning mode by second harmonic (wavelength λ = 532 nm) of a Q-switched YAG:Nd laser. The effect of laser irradiation was studied by Raman and infrared spectroscopy and spectroscopic ellipsometry. The changes in the optical spectra of the samples with different H amount were investigated in the dependence on laser intensity. Experimental data were interpreted taking into account the structural transformations of a-C:H films.

Keywords: amorphous diamond-type carbon films, laser irradiation, optical properties

PACS: 78.66.Jg, 61.80.Ba, 78.20.-e

AMORFINIŲ a-C:H DANGŲ MODIFIKAVIMAS LAZERIO APŠVITA
A. Grigonis^a, Ž. Rutkūnienė^a, A. Medvid^b, P. Onufrijevs^b, J. Babonas^c
^aKauno technologijos universitetas, Kaunas, Lietuva
^bRygos technologijos universitetas, Ryga, Latvija
^cPuslaidininkių fizikos institutas, Vilnius, Lietuva

Joniniu spinduliniu nusodinimo metodu acetileno bei acetileno/vandenilio mišiniuose ant silicio pagrindo buvo suformuotos amorfinės hidrogenizuotos panãšios į deimantą anglies dangos (a-C:H). Apšvitai koherentinės šviesos kvantais naudotas YAG:Nd impulsinis lazeris, kurio impulso trukmė 10 ns, pasikartojimų dažnis 12,5 Hz, spindulio skersmuo 2,5 mm, skanavimo žingsnis 25 µm, apšvitos galia 1,8–10,2 MW/cm². Lazerio apšvitos įtaka buvo tirta Ramano, infraraudonosios spektroskopijos bei spektrinės elipsometrijos metodais. Tyrimai parodė, kad, esant skirtingoms vandenilio koncentracijoms dangose, jų optiniai spektrai kinta priklausomai nuo lazerio intensyvumo. Didžiausius pokyčius dėl koherentinės spinduliuotės poveikio patiria turinčios daug sp² ryšių, t. y. daug grafito fazės; jos savo savybėmis artimos panašioms į grafitą anglies dangoms. Esant tam tikrai apšvitos galiai, kuri priklauso nuo to, kiek dangoje yra sp³ fazės ir kiek vandenilio dalyvauja sudarant šią fazę, šios dangos virsta stiklo anglimi. Taip pat nustatyta, kad lazerio spinduliuotė gali sukelti SiC bei į deimantą panašių kristalitų susidarymą dangose.

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