Role of electronic excitation in phase-change memory materials: A brief review.

Phase-change memory (PCM) materials, such as chalcogenide alloys, have the ability for fast and reversible transition between their amorphous and crystalline states. Owing to the large optical/electrical contrast of the two states, PCM materials have been developed for data storage. It has been generally accepted that thermal effects, caused by laser irradiation or electrical pulses, control the amorphization by melting the sample and subsequent quenching, while crystallization is realized by thermal annealing. An important element that has not been considered extensively, however, is the role of electronic excitation by optical or electrical pulse. Strictly speaking, until electrons and holes recombine, the system under external stimulus is in a non-equilibrium environment, especially when the excitation intensity is high. This raises an important question: can the excitation alone induce phase transition for PCM data storage without the usual thermal melting? Here, we will review the recent experimental and theoretical indications and evidence in support of the electronic excitation-induced phase change in PCM materials and discuss potential ramifications of the athermal phase-change phenomenon for data storage. [ABSTRACT FROM AUTHOR]