A review of in situ transmission electron microscopy study on the switching mechanism and packaging reliability in non-volatile memory

Non-volatile memory(NVM)devices with non-volatility and low power consumption properties are important in the data storage field.The switching mechanism and packaging reliability issues in NVMs are of great research interest.The switching process in NVM devices accompanied by the evolution of microstructure and composition is fast and subtle.Transmission electron microscopy(TEM)with high spatial resolution and versatile external fields is widely used in analyzing the evolution of morphology,structures and chemical compositions at atomic scale.The various external stimuli,such as thermal,electrical,mechanical,optical and magnetic fields,provide a platform to probe and engineer NVM devices inside TEM in real-time.Such advanced technologies make it possible for an in situ and interactive manipulation of NVM devices without sacrificing the resolution.This technology facilitates the exploration of the intrinsic structure-switching mechanism of NVMs and the reliability issues in the memory package.In this review,the evolution of the functional layers in NVM devices characterized by the advanced in situ TEM technology is introduced,with intermetallic compounds forming and degradation process investigated.The principles and challenges of TEM technology on NVM device study are also discussed.

Facile fabrication of paper-based flexible thermoelectric generator

Paper,as a foldable,pollution-free,and low-cost material,has become a suitable support substrate for producing flexible thermoelectric(TE)generators to realize waste heat recycling and the application of human-powered electronic devices.We propose a facile fabrication method to modify cellulose paper with inorganic TE powders via vacuum filtration,making a modified paper that possesses good thermoelectric properties.By connecting the modified paper to copper foils,flexible paper-based TE generators(PTGs)are fabricated.The obtained PTG with three units of P–N modules can generate an output voltage of∼41.2 mV at a temperature difference of 50 K.Based on this modified paper,a thermal sensor that responds to heat sources,such as fingers,is proposed with a rapid response time of 0.25 s.This work offers a promising strategy for the simple fabrication of PTGs,paving the way for achieving the commercial application of self-powered wearable electronics.