Specific Contact Resistance of Phase Change Materials to Metal Electrodes

For phase change random access memory (PCRAM) cells, it is important to know the contact resistance of phase change materials (PCMs) to metal electrodes at the contacts. In this letter, we report the systematic determination of the specific contact resistance (ρ
c
) of doped Sb
₂
Te and Ge
₂
Sb
₂
Te
₅
to TiW metal electrodes. These data are reported for both the amorphous and the crystalline states of these PCMs. The temperature and voltage dependences of ρ
c
are also studied. A detailed understanding of these contacts is essential for the scaling, design, device modeling, and optimization of PCRAM cells.