Glow discharge condition

Fig. 4.37. Depth (temporal) profile obtained on a multilayer coating produced by plasma vapor deposition (PVD) using optimized rf-glow discharge conditions. Layer thickness ...

Figure 3. Partial pressures of the residual gases CHh (16 amu) and CO/C2Hh (28 amu) (a) produced during H2 glow discharge conditioning (GDC) of the PDX vessel. At the indicated arrows, the torus was exposed to atmospheric pressure for several hours. Residual gas production (b) during GDC immediately after atmospheric exposure. (Reproduced, with permission, from Ref. 37.

Figure 14.1 Confining effect of magnetron glow discharge. The upper and lower reactors have identical electrode systems, except that the upper electrodes have no magnetic enhancement and are operated at identical glow discharge conditions. Argon, 0.40 cm sxp/iiiin 46mtorr 5W 10 kHz.

Cathode spot (plasma technology) The area on the cathode, under normal glow discharge conditions, in which the current is concentrated. As the current increases, the spot becomes bigger in order to maintain a constant current density in the cathode spot. In an Abnormal glow discharge, the cathode spot covers the whole cathode area. 

Diagnostic techniques that involve natural emissions are appHcable to plasmas of all sizes and temperatures and clearly do not perturb the plasma conditions. These are especially useful for the small, high temperature plasmas employed in inertial fusion energy research, but are also finding increased use in understanding the glow discharges so widely used commercially. 

To maintain reproducible excitation conditions in the glow discharge source, the working conditions (e. g. argon pressure, dc-current or rf-power) are carefully controlled. 

Table 8.60 shows the main features of GD-MS. Whereas d.c.-GD-MS is commercial, r.f.-GD-MS lacks commercial instruments, which limits spreading. Glow discharge is much more reliable than spark-source mass spectrometry. GD-MS is particularly valuable for studies of alloys and semiconductors [371], Detection limits at the ppb level have been reported for GD-MS [372], as compared to typical values of 10 ppm for GD-AES. The quantitative performance of GD-MS is uncertain. It appears that 5 % quantitative results are possible, assuming suitable standards are available for direct comparison of ion currents [373], Sources of error that may contribute to quantitative uncertainty include sample inhomogeneity, spectral interferences, matrix differences and changes in discharge conditions. 

Figure 16 (Street et al., 1986) shows the typical sample structure, consisting of three layers of a-Si H. Results using this technique have been reported for samples grown by the rf glow discharge of silane and by rf sputtering (Shinar et al., 1989). The first layer is hydrogenated amorphous silicon, deposited under conditions that yield high quality films (i.e., deposition temperature of 230°C, low growth rate) and is typically two microns thick. Next a layer of approximately 1000 A is deposited, whereby...

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