The discharge voltage was measured for 15 different metallic target materials at constant current before and after plasma oxidation in order to understand its behavior during reactive magnetron sputtering. Plasma oxidation of the target surface was achieved by sputtering the target in pure oxygen. The discharge voltage measured in pure argon is characteristic for each kind of metallic target and is related to the ion induced secondary electron emission (ISEE) coefficient of the target material. Based on this relation a value for the ISEE coefficient of the oxidized target surface can be calculated. Two distinct groups can be discerned: for one group the ISEE coefficient of the oxidized target surface is larger than the ISEE coefficient of the metal, while the opposite behavior is noticed for the second group. This difference seems to find its origin in the reduction behavior of the oxides under ion bombardment, since the ISEE coefficient of the oxide can be related to the simulated degree of reduction of the oxide. It is shown that the ISEE coefficient of the reduced oxides decreases with increasing oxygen content in the target. This is confirmed experimentally by sputtering in pure argon reduced titanium oxide targets with a known composition.

Vanadium pentoxide was deposited by atomic layer deposition (ALD) from vanadyl-tri-isopropoxide (VTIP). Water or oxygen was used as a reactive gas in thermal and plasma-enhanced (PE) processes. For PE ALD, there was a wide ALD temperature window from 50 to 200°C . Above 200°C , VTIP decomposed thermally, resulting in the chemical vapor deposition (CVD) of vanadium pentoxide. The PE ALD reactions saturated much faster than during thermal ALD, leading to a growth rate of approximately 0.7 Å/cycle during PE ALD using normalH2O or normalO2 . Optical emission spectroscopy showed combustion-like reactions during the plasma step. X-ray diffraction was performed to determine the crystallinity of the films after deposition and after postannealing under He or normalO2 atmosphere. Films grown with CVD at 300°C and PE normalO2 ALD at 150°C were (001)-oriented normalV2normalO5 as deposited, while thermal and PE normalH2O ALD films grown at 150°C were amorphous as deposited. The crystallinity of the PE normalO2 ALD could be correlated to its high purity, while the other films had significant carbon contamination, as shown by X-ray photoelectron spectroscopy. Annealing under He led to oxygen-deficient films, while all samples eventually crystallized into normalV2normalO5 under normalO2 .

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