Plasma anodization is the formation of thin oxide films by placing the metal or semiconductor substrate under bias in the field of an oxygen plasma. Thus, plasma anodization is not a deposition process but rather an in situ film growth process. A positive bias of a few to several hundred volts is placed on the sample to affect film growth. Ions in the discharge are now more actively participating in the film growth, in contrast to much less participation by ions on floating or grounded substrates. Reviews of plasma Anodization have summarized a good deal of this work to which the reader is referred.