Three main processes are involved in reactive deposition. The main process of deposition is sputtering on the target surface. Simultaneously, when reactive gas is introduced into the deposition chamber, getter processes occur on the target surface, the substrate surface, and the chamber walls of the deposition equipment. Getter processes occur when layers are formed by the interaction of reactive gas atoms. They take place in various forms on all surfaces in a coating system.  Getter processes that take place on the target surface are also known as "target poisoning". The reaction with reactant gas, as the supply increases, causes the sputtering yield to decrease because of the increasing occupancy of the target. The secondary electron yield increases and the plasma impedance decreases, resulting in a reduced cathode voltage at the magnetron. The sum of the events leads to a hysteresis behavior in the process of reactive magnetron sputtering. While the stoichiometry in the deposition of nitrides can often be controlled relatively easily via the partial pressure of the reactive gas, the process of target poisoning in the reactive sputtering of oxides behaves much more dynamically and is therefore more difficult to control with conventional DC magnetron sputtering. As the target surface is also covered by an oxide layer during the deposition process, the resulting lower electrical conductivity of the oxide layer leads to increased arcing. Arcing leads to an extremely unstable sputtering process, creates undesired droplets of molten target material and can even destroy the sputtering target. The choice of a pulsed DC source for magnetron sputtering can overcome these disadvantages. The pulsed mode of the magnetron with frequencies ranging from 100 kHz to 350 kHz avoids arcing on the target surface, since it is covered with oxide layer.