Carrier Type Exchange with the Sweep Direction in a WORM Memory Device

In the present study, we have investigated the charge transport mechanism of the resistive switching phenomenon of a write-once-read-many-times (WORM)-type memory device. Phenol red sodium salt (PRSS), a xanthene dye, has been used as the active layer. Gold (Au) and ITO have been used as top and bottom electrodes, respectively. The electron transport and hole transport mechanisms predominate in positive and negative sweep voltages, respectively. This has been confirmed from density functional theory calculations of HOMO and LUMO levels and also from theoretically calculated values. The device showed WORM-like behavior when the thickness of the active layer was greater than 200 nm. The device also showed a high retention time and a high memory window with a good device yield and a good number of endurance cycles. The device also showed good thermal, humidity, and aging stability. As a whole, this device showed interesting features regarding different charge transfer processes in two different sweep directions, which can further be considered as an efficient resistive memory device.