Electrically erasable nonvolatile optical MNOS memory device

A new type of nonvolatile optical memory device composed of a MNOS FET with a photosensitive region is proposed. Based upon charge transport induced by voltage change across a double insulator layer under illumination, the present device can be operated in a broad wavelength spectrum from the infrared to the visible region when provided with a d.c. bias voltage. It is found that the charge transport is a function of the exposure time as well as of the intensity of the incident light. An operation mechanism is proposed based upon the experimental results.