Contact resistivity of amorphous and crystalline GeCu2Te3 to W electrode for phase change random access memory

We have investigated the contact resistivity of GeCu2Te3 (GCT) phase change material to a W electrode using the circular transfer length method (CTLM). The contact resistivity ρc of as-deposited amorphous GCT to W was 3.9×10−2 Ω cm2. The value of ρc drastically decreased upon crystallization and crystalline GCT that annealed at 300 °C showed a ρc of 4.8×10−6 Ω cm2. The ρc contrast between amorphous (as-deposited) and crystalline (annealed at 300 °C) states was larger in GCT than in conventional Ge2Sb2Te5 (GST). Consequently, it was suggested from a calculation based on a simple vertical structure memory cell model that a GCT memory cell shows a four times larger resistance contrast than a GST memory cell.