A study is conducted to investigate the relative advantages of different driving devices for phase-change memory cells using 3-D numerical device simulation. Among various possible choices, p-n diodes and vertical gate-all-around (GAA) metaloxidesemiconductor field-effect transistors (MOSFETs) are studied in detail as they represent distinct classes of driving devices. Different performance parameters including cell size, current drive, disturb immunity, power dissipation, and scalability are carefully compared. While p-n diodes show superiority in technology nodes with large device dimensions, the scaling process has improved the performance of GAA MOSFETs significantly to outperform that of p-n diodes in extremely scaled technologies. © 2011 IEEE.