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What Is Phase-Change Memory?

Alex Newth
Alex Newth

Phase-change memory is a type of random access memory (RAM) chip that uses the phase-changing abilities of chalcogenide glass. This glass is able to change states based on heat and current, and phase-change memory literally changes its physical state during operation, which leads to higher memory capacity. Like many other RAM chips, phase-change is non-volatile, which often is a more permanent and better-functioning type of memory. One of the major problems with using and creating this type of memory also is its advantage: heat and current cause the memory to change state, so these must be effectively controlled.

Most RAM chips are made from electronic components, but phase-change memory adds another material to the chip. Chalcogenide glass has been used for many products, such as compact discs (CDs), and it is able to change its physical state as a response to heat and current. The two common states through which this glass goes are amorphous and crystalline; both are very different and give this RAM chip advantages over other types.

Woman doing a handstand with a computer
Woman doing a handstand with a computer

The most distinct advantage phase-change memory has over other memory chips is an increased memory threshold. Each state is different, so memory can be equally stored in each state. This means phase-change RAM often can hold two times as much memory as other RAM chips. This leads to better RAM performance and enables a computer to use smaller chips so the entire system can be made smaller.

Many RAM chips are non-volatile, and phase-change memory belongs to this classification. When a computer is turned off, electricity drains from all the hardware pieces, which may or may not lead to the loss of RAM memory. If the chip is volatile, then this loss of electricity will cause the memory to disappear, while non-volatile chips hold the memory for hours. While this may not be useful if the computer is turned off for a long time, it allows phase-change RAM to easily boot up a computer if the memory still is stored.

While phase-change memory has an advantage because it can change states, this also is a problem when making a stable phase-change RAM chip. Heat and current change the memory’s state, so both of these factors must be controlled or the memory capacity may be decreased. This means computers using this type of memory often need strong hardware pieces that keep heat and current stable, even during high processing times.

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      Woman doing a handstand with a computer