Proposal for a memory transistor using phase-change and nanosize effects

We have proposed and demonstrated a memory transistor that has two functions of non-volatile memory action and electron current control (switching) using phase change (PC) and nanometer size effects. We have made a prototype transistor using a PC channel. The PC material was a GeSbTe thin film with a thickness of 50 nm. We demonstrated that the crystalline phase of the PC channel was changed to an amorphous phase, and the amorphous phase was changed to a crystalline phase by current heating of the channel. Furthermore, the channel current could be controlled by a gate bias. When the gate bias was made + 3 V, the source-drain current was suppressed to < 1/10 of that with a gate bias of -3 V. The proposed transistor promises to achieve an ultimate memory cell structure and to make an advance towards an ultra-high density non-volatile memory. (C) 2004 Elsevier B.V. All rights reserved.