Fasförändringsminne

Fasförändringsminne, often abbreviated as PCM (Phase-Change Memory), is a type of non-volatile random-access memory technology. It stores data by changing the physical state of a chalcogenide material, typically a germanium-antimony-tellurium alloy. This material can exist in two distinct phases: amorphous (disordered) and crystalline (ordered).

The fundamental principle behind PCM operation involves heating and cooling the chalcogenide material. Applying a short, high-current electrical pulse causes the material to heat rapidly, exceeding its melting point and then quenching it quickly into an amorphous state. This amorphous state represents one data bit, often a "0". Conversely, applying a longer, lower-current pulse heats the material to a temperature below its melting point but above its crystallization temperature, allowing it to slowly cool into a crystalline state. This crystalline state represents the other data bit, often a "1".

The difference in electrical resistance between the amorphous and crystalline states is significant, allowing a read operation to distinguish between the two states and thus read the stored bit. PCM offers advantages such as high endurance, fast read and write speeds, and excellent data retention. It is considered a promising candidate for next-generation memory technologies due to its potential to bridge the gap between volatile DRAM and non-volatile flash memory. Applications being explored include embedded memory in microcontrollers, main memory replacements, and storage-class memory.