Jiri Bulir

Inductively coupled plasma and laser-induced chemical vapour deposition of thin carbon nitride films

Abstract Thin CN x films have been deposited on silicon substrates by inductively coupled plasma chemical vapour deposition (ICP-CVD) and by laser-induced chemical vapour deposition (LCVD) utilizing the focused beam of a copper bromide vapour laser. Different gas mixtures were used: CH 4 /N 2 and CCl 4 /N 2 /H 2 for ICP-CVD, and CCl 4 /NH 3 for LCVD. Plasma properties (electron temperature, electron and ion densities, plasma potential) were studied by Langmuir probe and optical emission spectroscopy. The growth rates ranged up to 80 nm min −1 for ICP-CVD and 700 μm min −1 for LCVD. The surface morphology was studied using atomic force microscopy for ICP-CVD, and scanning electron microscopy for LCVD. Beside carbon and nitrogen, silicon and oxygen for LCVD and chlorine for ICP-CVD (in the case of the CCl 4 /N 2 /H 2 system) was detected by Auger electron spectroscopy. Fourier transform infrared (FTIR) spectroscopy was used to determine the chemical bonding structure. Bands assigned to C=C and C=N (graphite-like domains) and to C=H bonds were detected in the films deposited by both processes. In addition, different bands attributed to other types of carbon nitride bonds or to due to the presence of impurity atoms were observed in the FTIR spectra of the CN x films deposited by the ICP-CVD and LCVD. The results of both deposition techniques were compared and discussed on the base of the processes peculiarities.

Determination of optical properties of PLZT thin films using transmittance spectra processing

This investigation deals with determination of optical parameters of thin PLZT films prepared by pulsed laser deposition on fused silica substrates at different oxygen pressure. Film composition and structure are investigated by WDX and XRD. Defects concentration in the films is studied using triboluminescence. Changes of film refractive index n((lambda) ), extinction k((lambda) ) with wavelength in the spectral region 0.3 - 1.1 micrometers and film thickness d are determined as a result of transmittance spectra processing. Waveguiding properties of the films are investigated.

Nd-doped KGW crystalline waveguides fabricated by pulsed laser deposition

The KGW thin films doped with Nd were prepared by pulsed laser deposition (PLD) on MgO, YAG and YAP substrates at substrate temperatures (Ts) varied from 400 degree(s)C to 800 degree(s)C in oxygen ambient atmosphere. The influence of the Ts and type of substrate on the film properties including the structure, luminescence and refractive index was studied. The best crystalline structure and strongest fluorescence signal was achieved at higher Ts on YAG substrate.

Influence of additional rf discharge on the properties of carbon nitride thin films deposited by PLD

Nitrogen-rich carbon nitride films were prepared by pulse laser deposition (PLD) combined with additional r.f. and hollow cathode discharges on fused silica, stainless steel and silicon substrates. The properties of combination of laser plasma with concentrated r.f. or HC discharges were studied using an optical emission spectroscopy (OES). The composition of the films was measured by WDX method. The transmission spectra and plastic microhardnes of the films were also measured.

CNx films deposited using combined deposition method: pulsed laser deposition in the RF discharged nitrogen gas

Thin CNx films were deposited by pulsed laser deposition (KrF excimer laser) with additional radio-frequency discharge of the nitrogen gas. Nitrogen pressure was in the range from 1 to 40 Pa and r.f. power was adjusted to 100 W. The substrate temperature was changed in the range from room temperature to 800 degree(s)C. An influence of the substrate temperature on the film composition and structure was studied. The composition of the films was measured by wavelength dispersive x-ray spectroscopy. The N/C ratio of films deposited at room temperature almost reach 1; however, it decreased with increasing substrate temperature. Structure was studied using Fourier transformed infrared spectroscopy analysis. Presence of CequalsC, CequalsN, CequalsVN, N-H and O-H groups was confirmed. Optical properties were analyzed using UV-VIS reflection spectroscopy.

RF- and dc-plasma-assisted laser deposition of a-CNx thin films

Carbon nitride thin films are candidates for various technological applications. Special kind of a-Cnx film, as (beta) -C3N4, is supposed to be material exhibiting extreme hardness--higher than diamond. Many groups are trying to synthesize a-CNx films (with goal of creation (beta) -C3N4 phase), but concentration of nitrogen in films is still low. We have created series of nitrogenated amorphous carbon films in nitrogen atmosphere from graphite target by pulsed laser deposition. Additional DC and RF discharges were ignited in order to increase the reactivity of the nitrogen. Film properties were analyzed by X-ray diffraction and spectroscopic ellipsometry. The effects of the discharges on the C-N stoichiometry and on chemical bonding were studied. The N/C ratio increased with higher RF and DC plasma densities up to value of 0.25. Maximum values were reached at the nitrogen pressure twice lower for rf discharge than dc discharge assisted deposition. C-N stoichiometry and chemical bonding were investigated by Fourier transform infrared spectroscopy, X- ray Photoelectron Spectroscopy and Raman spectroscopy. Only films deposited at higher rf plasma power density showed the presence of triple bonded C equalsV N stretching mode.