On-nanowire heteroepitaxial integration of diode and PRAM

Phase change random access memory (PRAM) has been the subject of considerable recent interest as next-generation nonvolatile data storage, offering good cycling endurance, extended scalability, and reduced switching times. A linear integration of a phase change memory (PCM) cell and a p-n diode can be an interesting architecture, since it can further increase the area density of PCM cells by minimizing single memory-cell sizes. In the early stage of heteroepitaxial integration of a PCM and a diode, we report the synthesis of Si nanowire (NW) p-n diode and PCM NW as an each segment of integrated PRAM cell. Axially modulated Si NW diode has been successfully achieved by catalytic chemical vapor syntheses vapor-liquid-solid (VLS) mechanism and complementary doping. Spatially resolved scanning photocurrent measurement was used for the verification of p-n junction within Si NW diode. PCM NW was synthesized via metal catalyst-assisted vapor transport method. Through electrical measurements, key parameters for device performance such as memory-switching curves, write/erase currents, and threshold voltages were investigated.