IBAD technique

Fig. 16 Raman spectrum of DLC film deposited by IBAD technique.

Figure 16 shows the Raman spectrum of a DLC film deposited by the IBAD technique. The Raman spectra for diamond like materials provide information on the sp bonding. The characteristic features of Raman spectra of diamond like materials consist of a graphite-like (G) peak and a disorder (D) peak in the regions 1500-1550 cm and 1330-1380 cm respectively. The relative intensities of the G and D peaks can be used to indicate qualitatively the concentration of graphite crystallites of... 

Fig. 22 RBS spectra of carbonitride films deposited, at different temperatures, using IBAD technique.

Gulla et al. have demonstrated superior performance and stabUily of carbonless thin layer electrodes made by a dual ion beam assisted deposition (IBAD) technique that combines physical vapor deposition (PVD) with ion beam bombardment [47]. They found that bilayered coatings on GDL with either a Co or a Cr iimer layer ( 50 nm thin) and a Pt outer layer ( 50 nm thin, and 0.08 mg Pt cm ) showed a more than 50% higher Pt mass activity at 900 mV than a Pt single layer. 

Du et al. (1998) reported, based on their study of the interaction between osteoblasts (isolated from 4-day-old Wistar rats) and DLC as well as carbon nitride (CN) thin films (obtained by ion beam—assisted deposition (IBAD) technique), that the osteoblasts attach, spread and proliferate on both DLC and CN sample surfaces without apparent impairment of cell physiology. 

Based on their study of neutral granulocyte—neutrophil interaction with DLC (obtained by IBAD technique) coated PMMA lOLs, Li et al. (1999) reported that DLC-coated PMMA lOLs exhibit lower neutrophil adhesion compared with uncoated PMMA lOLs. 

Figure 22 shows RBS spectra of amorphous (Raman spectra similar to amorphous diamond like films) carbonitride films deposited at different temperatures using IBAD. Using this technique, maximum nitrogen incorporation was 33% as compared to 57% required for P-C3N4 stoichiometry. The XPS spectra (C Is and N Is) of the film with 33% nitrogen are shown in Figure 23. From these spectra the percentage of single bonded carbon and nitrogen is obtained...

Two recent techniques that have come to be applied to compound semiconductors and oxides are pulsed laser deposition (PLD) also known as laser ablation [6] and ion beam assisted deposition (IBAD) [2-8]. These techniques have been developed for films whose elemental constituents are not easily volitalized in elemental or organome-tallic forms or whose formation can benefit from the added energy imparted to the reactants by the process. 

IBAD, as shown in Figure 4-10, as applied to compound semiconductors, also is a relatively new technique, and as with PLD is primarily under development to produce films which have no other direct and convenient means of fabrication. In IBAD, an ion beam is formed and directed at the deposition plane. One or more ion beams may be combined with gas or plasma fluxes, as well as evaporator hearths or other sources. This technique also has been used to form epitaxial films. 

An alternative technique combining PVD and ion implantation is known as Ion Beam Assisted Deposition (IBAD), where the film is bombarded by an ion beam during its deposition, thus typically improving the density, structure, and adhesion of the coating. 

Ion beam-assisted deposition (IBAD) utilizes a separate vaporization source and bombardment source and is often classed as a deposition technique, separate from ion plating. Figure 9.1(b) shows one IBAD configuration. One advantage of the IBAD process is that, in it, the ion flux can be measured directly using a Faraday cup ion collector (Ch. 5) and atom flux can be measured using a mass deposition monitor such as a QCM. A disadvantage is that... 

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