Stored charges in relatively thin oxide films

Surface potential difference changes at arc cathode and anode tracks on nonrefractory metals are reported which show storage of charge in oxide films of less than 100 Å thickness. These charges decay only slowly and can even reverse in sign after some time. This suggests the possibility of electret properties which have only previously been reported for films of about 1000 Å thickness. Other mechanisms which may be responsible for charge storage are discussed, such as oxygen and water chemisorption and a forming process similar to that which is being extensively investigated in amorphous oxide layers from 100 Å to 20 000 Å thick in connection with switching and memory phenomena.