Anodisation can be carried out using either a constant voltage source or a constant current source. In the case of constant voltage source anodisation, the oxide thickness builds up towards a final value. The final thickness is proportional to the applied voltage and typically the value is about 0.3 nm/V for silicon. When the anodisation is carried out from a constant current source, the oxide thickness varies linearly with time. In this case, the electric field across the oxide is constant and the voltage drop across it increases with time. The linear increase of voltage can be monitored and the process can be stopped when the desired oxide thickness is reached.

Oxides formed by anodisation are generally porous in character, and have water incorporated in them. During the anodic oxidation process, semiconductor material is transferred through the oxide to the electrolyte-oxide interface. Thus, anodised oxide has an interface charge density about one order of magnitude larger than that of the conventional thermal oxide. From the above discussions on thermal oxidation and anodic oxidation of silicon, it is clear that thermal oxidation results in better quality SiO₂ as well as a better Si-SiO₂ interface compared to anodic oxidation.

In this section we have studied thermal oxidation of silicon and basic model which describes the oxidation process of silicon. Briefly we have discussed about the anodic oxidation process also. In the next section we will take up the methods by which films of various materials are deposited on silicon.