Phase-change memory

Phase-change memory (also known as PCM, PCME, PRAM, PCRAM, OUM (ovonic unified memory) and C-RAM or CRAM (chalcogenide RAM)) is a type of <a href="/facts/Non-volatile_random-access_memory/CIYnqh4E">non-volatile random-access memory</a>. PRAMs exploit the unique behaviour of <a href="/facts/Chalcogenide_glass/6Lug8YLy">chalcogenide glass</a>. In PCM, heat produced by the passage of an <a href="/facts/Electric_current/Dc1xdnUX">electric current</a> through a <a href="/facts/Heating_element/q0GLQufX">heating element</a> generally made of <a href="/facts/Titanium_nitride/vxbbBgNz">titanium nitride</a> is used to either quickly heat and <a href="/facts/Quenching/UUCW0GQD">quench</a> the glass, making it <a href="/facts/Amorphous_solid/YTIzmrR0">amorphous</a>, or to hold it in its crystallization temperature range for some time, thereby switching it to a <a href="/facts/Crystal/e2R2mk3E">crystalline</a> state. PCM also has the ability to achieve a number of distinct intermediary states, thereby having the ability to hold multiple <a href="/facts/Bit/S972NSaD">bits</a> in a single cell, but the difficulties in programming cells in this way has prevented these capabilities from being implemented in other technologies (most notably <a href="/facts/Flash_memory/Cn8JsStx">flash memory</a>) with the same capability.
Recent research on PCM has been directed towards attempting to find viable material alternatives to the <a href="/facts/Phase-change_material/NDVVyXs3">phase-change material</a> <a href="/facts/GeSbTe/HEyUwYwK">Ge2Sb2Te5</a> (GST), with mixed success. Other research has focused on the development of a <a href="/facts/Germanium/wtoALHGs">Ge</a><a href="/facts/Tellurium/v7QvfIvS">Te</a>–<a href="/facts/Antimony/YsA7lVgT">Sb</a>2Te3 <a href="/facts/Superlattice/nguy8U7X">superlattice</a> to achieve non-thermal <a href="/facts/Phase_transition/eLP2BY8R">phase changes</a> by changing the co-ordination state of the germanium atoms with a <a href="/facts/Laser/jk6PTvvT">laser</a> pulse. This new Interfacial Phase-Change Memory (IPCM) has had many successes and continues to be the site of much active research.
<a href="/facts/Leon_Chua/v5DWrV5E">Leon Chua</a> has argued that all two-terminal <a href="/facts/Non-volatile_memory/EN72wMD9">non-volatile-memory</a> devices, including PCM, should be considered <a href="/facts/Memristor/BrFKeE7l">memristors</a>. <a href="/facts/R._Stanley_Williams/5ldcuuwv">Stan Williams</a> of <a href="/facts/HP_Labs/Pq3NGJh4">HP Labs</a> has also argued that PCM should be considered a memristor. However, this terminology has been challenged, and the potential applicability of memristor theory to any physically realizable device is open to question.

Phase-change memory open-in-new

Phase-change memory