Physical model of low-frequency noise in Phase-Change Memory devices
Thomas Bohnstingl
11:15 - 12:15 Wednesday 20 May 2020 PH 01 150 Link to the talk
Phase-Change materials (PCM) are an emerging class of materials which have formed the basis for Compact Discs (CDs), Digital Versatile Discs (DVDs) and were recently also commercialized as storage-class memories. In contrast to charge-based devices such as DRAM or Flash, PCMs store information in their phase configuration, which can gradually change from an amorphous configuration to a poly-crystalline configuration.
These devices are also being explored for applications in the domain of machine learning, in particular, as non-von Neumann-based accelerators for deep learning, where they are arranged in crossbar structures to efficiently carry out vector-matrix multiplications.
Despite their versatile applications, PCM devices feature pronounced low-frequency noise, which has not been studied extensively and the underlying physical mechanism is still under debate. This noise poses a fundamental limitation for applications such as deep learning accelerators, where it limits the effective precision with which operations are carried out. Moreover, the 1/f noise is detrimental for PCM-based storage cells, especially if multiple bits of information are to be stored on a single device. Therefore, a better understanding of the noise behavior could potentially pave a way towards increased storage density and more reliable PCM devices.
The aim of this work is to investigate the physical phenomena of low-frequency noise in PCM devices. Physical models proposed in the literature are reviewed and evaluated on Ge2Sb2Te5 (GST) under different phase configurations. Specifically large temperature ranges from around 77K to above room temperature are investigated.
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Institute of Solid State Physics
