Anodic Behavior - Electrochemistry of Silicon and Its Oxide - page 207

species at the silicon/oxide interface, (2) surface reconstruction (e.g., hydrogen termi-
nation, or termination) which may or may not stabilize the surface, and (3)
dissolution of silicon substrate during the reconstruction process.

5.10. CURRENT OSCILLATION

Current oscillation is a phenomenon that has been observed to occur during the
anodic polarization of silicon in fluoride-containing solutions in the potential region of
1.5 to 602,860,939 Depending on the specific system, oscillation may occur sponta-
neously or by a perturbation of the potential. 693
The occurrence of current oscillation is independent of doping type; it is identi-
cal for p -type and strongly illuminated n -type materials. It, however, depends strongly
on solution composition. The data from the literature indicate that in HF solutions, sus-
tained oscillation is observed only above 1.8% HF and below 5% HF. Below 1.8% HF,
the oscillation is damped, whereas above 5%, the oscillation becomes chaotic. 122 At pH
below 2.5, the oscillation disappears after a certain time and the stationary current
remains relatively high. At pH above 5, the oscillation also disappears after a certain
time. 544 Oscillation is also observed in non-aqueous solutions such as MeCN-xF, where
x represents non H ligand. 1071 In addition, the occurrence of oscillation depends on oper-

ating procedures such as scanning speed, series resistance in the circuit, or perturba-
tion during the anodic polarization.

5.10.1. Amplitude and Frequency

The characteristics of the oscillation in terms of amplitude, frequency, and
their variation with time depend on solution composition as shown in Fig. 5.49. 860