Search

Metal–ferroelectric (FE)–metal structures with amorphous WOx bottom electrodes (BEs) are experimentally and theoretically demonstrated to favor the FE orthorhombic phase formation. The ferroelectric tunnel junction (FTJ) using the amorphous WOx BE and ZrO2-HfO2 superlattice FE layer has a remanent polarization of $70~\mu \text{C}$ /cm2. The FTJ has high endurance of 1E12 and 1E8 cycles for the write operation with incomplete and complete polarization switching, respectively. The write and read voltages have record low values of 1.3 and −0.15 V, respectively. The −0.15-V read does not cause read disturbance due to no polarization switching. The thermal budget is as low as 450 °C.

Aptamers are a type of single stranded short deoxyribonucleic acid or ribonucleic acid sequences screened from a random oligonucleotide library, which have high affinity and specific recognition for specific target molecules. Since the advent of screening process called the systematic evolution of ligands by exponential enrichment (SELEX), there have been various SELEX-based improved screening processes and capillary electrophoresis-based SELEX or non-SELEX selection processes. As a molecular recognition element similar to antibody, aptamers have been applied to the detection of residues of pesticide and veterinary drugs associated with food and environmental safety. In these applications, aptamers are usually formed composite probes with other materials to produce signals, such as gold nanoparticles, quantum dots, or constitute sensors with electrochemical electrode. These screening methods and the applications of aptamers in the detection of pesticide and veterinary drug residues are summarized to provide a helpful reference for these issues.