Thickness Dependences of Phase Change and Channel Current Control in Phase-Change Channel Transistor

We investigated electrical properties on phase change and channel current control effect in phase-change channel transistors with a 10-nm- to 200-nm-thick Ge2Sb2Te5film channel by Joule heating and annealing. I-V characteristics showing a phase change by Joule heating were measured. The current switching from an amorphous to crystalline state is about 2μA. A channel current control effect by the gate voltage since Joule heating in 50-nm- to 200-nm-thick devices was observed but not strong. Switching to the lowly resistive state in devices with an ultrathin channel was difficult, which might be due to large voids forming in the heated Ge2Sb2Te5channel. After annealing, drain-source resistance of devices dropped by about 3 orders of magnitude owing to phase change. A clear channel current control effect was observed especially for devices with an ultrathin channel. There exists a strong thickness dependence of channel current control effect.