Abstract. The basic process at the surface of the Si electrode is characterized by a cyclic oxidation of a thin silicon layer and the subsequent removal of the oxide by etching. Here, the oxide thickness evolves not uniformly due to cracks and nanopores. The mathematical model used to describe the phenomenon is based on a sequence of time dependent (oxide thickness) oscillator density functions that describes the passing of the (infinitesimal) oscillators through their minimum at each cycle. Two consecutive oscillator density functions are connected by a second order linear integral equation representing a Markov process. The kernel of the integral equation is a normalized Greens Function and represents the probability distribution for the periods of the oscillators during a cycle. Both, the oscillator density function and the twodimensional probability density for the periods of the oscillators, define a random walk. A relation between the oscillator density functions and solutions of the Fokker-Planck equation can be constructed. This allows a connection of the oscillations, originally considered only for the description of a photo-electrochemical observation, to the Schrödinger equation. In addition, if the trajectory of a virtual particle, located at the silicon oxide electrode surface, is considered during one oscillatory cycle, then it can be shown that the displacement of the particle measured at the electrode surface performs a Brownian motion.
IntroductionOscillation phenomena of silicon electrodes in electrochemical systems have been known for a long time [1]. In photo-electrochemistry and electrochemistry, oscillatory behaviour has been extensively studied on Si photo-electrodes [2]. Various models for the oscillation phenomena were discussed based on self-oscillating domains [3], the so-called current bursts [4], and oxide-induced interfacial stress [5] where the latter model explains sustained current oscillations with the existence of two types of oxides with different nanopore densities. The observation of nano-dimensioned pores, fluctuating with the phase of the oscillating (photo) current of Si electrodes immersed in dilute ammonium fluoride solutions motivated the further development [6][7][8] of the original stress model, also to spatial resolution, by applying cellular automates [7]. If the model is presented by a special phase space analysis based on the holographic principle [9][10], then an analogy between the spectral energy densities of the black body radiation and that obtained from the model for current oscillations can be shown [10]. We first describe (section 2) the mathematics of the model and the relation to the FokkerPlanck and Schrödinger equation. The Brownian motion of a virtual particle, which position is defined by an infinitesimal point located at the silicon surface, is discussed in section 3.