A short overview is given on deposition and integration of PZT thin films on silicon for MEMS applications. The application principles are explained and the piezoelectric coefficients are compared with the ones of AlN and ZnO. The Materials figure of merits are given for various applications and discussed. The coupling coefficient for ultrasonic applications is treated in more detail.

Piezoelectric thin films for mems

High-performance piezoelectric thin films generally contain toxic lead that limits the application scenarios especially in wearable and medical devices. Alternative lead-free piezoelectric materials such as Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) have been proved to have high biocompatibility and competitive piezoelectric performances. However, few have reported BCZT thin films integrated within flexible electronics. To fill this gap, we prepare BCZT thin films on flexible mica substrates and based on that fabricate piezoelectric nanogenerators (PENGs). The piezoelectric modulus d33 of the BCZT thin films evaluated from the established system reaches 150 pC N−1, which is comparable to those of films grown on single crystal substrates. The BCZT-based PENG can charge capacitors under mechanical excitation, indicating that it has broad application prospects in the field of flexible self-powered electronics.

A flexible and lead-free BCZT thin film nanogenerator for biocompatible energy harvesting

The rise of AI optoelectronic Sensors: from nanomaterial synthesis, device design to practical application

Piezoelectric thin films for MEMS

Resistive memories are outstanding electron devices that have displayed a large potential in a plethora of applications such as nonvolatile data storage, neuromorphic computing, hardware cryptography, etc. Their fabrication control and performance have been notably improved in the last few years to cope with the requirements of massive industrial production. However, the most important hurdle to progress in their development is the so‐called cycle‐to‐cycle variability, which is inherently rooted in the resistive switching mechanism behind the operational principle of these devices. In order to achieve the whole picture, variability must be assessed from different viewpoints going from the experimental characterization to the adequation of modeling and simulation techniques. Herein, special emphasis is put on the modeling part because the accurate representation of the phenomenon is critical for circuit designers. In this respect, a number of approaches are used to the date: stochastic, behavioral, mesoscopic..., each of them covering particular aspects of the electron and ion transport mechanisms occurring within the switching material. These subjects are dealt with in this review, with the aim of presenting the most recent advancements in the treatment of variability in resistive memories.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/aisy.202200338

Variability in Resistive Memories

[0 0 1]-oriented crystalline Potassium-Sodium Niobate thin film fabricated at low temperature for use in piezoelectric energy harvester

Engineering Synaptic Plasticity through the Control of Oxygen Vacancy Concentration for the Improvement of Learning Accuracy in a Ta2O5 Memristor

Structural and piezoelectric properties of textured NLKNS-CZ thick films and their application in planar piezoactuator

Physical properties of crystalline NaNbO3 thin film grown on Sr2Nb3O10 nanosheets at low temperatures for piezoelectric energy harvesters

• Crystalline Na 1-x K x NbO 3 (CNKN) film grown on Sr 2 Nb 3 O 10 (SNO) seed layer at 370 °C. • CNKN film grown on one SNO monolayer shows typical bipolar switching properties. • CNKN film grown on two SNO monolayers shows self-rectifying switching properties. • The CNKN memristor with two SNO monolayers shows artificial synaptic properties. • The CNKN film can be used to fabricate ANNs with a cross-point array structure. Crystalline (Na 1- x K x )NbO 3 (NKN) thin films were deposited on Sr 2 Nb 3 O 10 /TiN/Si (S-TS) substrates at 370 °C. Sr 2 Nb 3 O 10 (SNO) nanosheets served as a template for the formation of crystalline NKN films at low temperatures. When the NKN film was deposited on one SNO monolayer, the NKN memristor exhibited normal bipolar switching characteristics, which could be attributed to the formation and destruction of oxygen vacancy filaments. Moreover, the NKN memristor with one SNO monolayer exhibited artificial synaptic properties. However, the NKN memristor deposited on two SNO monolayers exhibited self-rectifying bipolar switching properties, with the two SNO monolayers acting as tunneling barriers in the memristor. The conduction mechanism of the NKN memristor with two SNO monolayers in the high-resistance state is attributed to Schottky emission, direct tunneling, and Fowler–Nordheim (FN) tunneling. The current conduction in this memristor in the low-resistance state was governed by direct tunneling and FN tunneling. Additionally, the NKN memristor with two SNO monolayers exhibited large ON/OFF and rectification ratios and artificial synaptic properties. Therefore, an NKN memristor with two SNO monolayers can be used for fabricating artificial synaptic devices with a cross-point array structure. 

In Su Kim

Papers

[0 0 1]-oriented crystalline Potassium-Sodium Niobate thin film fabricated at low temperature for use in piezoelectric energy harvester

Engineering Synaptic Plasticity through the Control of Oxygen Vacancy Concentration for the Improvement of Learning Accuracy in a Ta2O5 Memristor

Structural and piezoelectric properties of textured NLKNS-CZ thick films and their application in planar piezoactuator

Physical properties of crystalline NaNbO3 thin film grown on Sr2Nb3O10 nanosheets at low temperatures for piezoelectric energy harvesters

Artificial synaptic and self-rectifying properties of crystalline (Na1-K )NbO3 thin films grown on Sr2Nb3O10 nanosheet seed layers