Search

Cache-type phase-change random-access memory is a remaining challenge on the path to universal memory. The recently designed Sc0.2Sb2Te3 (SST) alloy is one of the most promising phase-change materi...

Na0.5Bi0.5Ti1−xZnxO3−δ (NBTZnx, x=0.005–0.04) thin films were deposited on indium tin oxide coated glass substrates by metal organic decomposition combined with sequential layer annealing. The effects of Zn2+ doping content on crystallization and dielectric tunability were mainly studied. All the thin films crystallize into a single perovskite structure with random orientation. Compared with the other films, the NBTZn0.01 film exhibits a high dielectric constant and strong nonlinear dependence of the dielectric constant on applied field due to its well-crystallization and high densification. Furthermore, the effects of the electric field and frequency on the dielectric constant-electric field characteristic for NBTZn0.01 film are discussed. The results show that NBTZn0.01 thin film with an enhanced dielectric tunability of 39% can be a lead-free candidate for tunable component.

Phase-change random-access memory (PCRAM) is the leading candidate to overcome the intrinsic bottleneck in current von Neumann architecture by unifying computing with storage, enabling its prospect as cognitive memory. However, strong resistance drift in current Ge2Sb2Te5-based PCRAM devices obstructs the accomplishment of high-accuracy computing tasks that require stable multi-state programming. Moreover, the implementation of synaptic depression still remains highly challenging for current PCRAM devices due to the abrupt amorphization nature. We employed 4 nm-thick monatomic antimony (Sb) film to achieve reliable iterative RESET and cumulative SET operations simultaneously, with considerably lowered resistance drift and programming noise. The 2D Sb-based device is also capable of performing progressive RESET operations. Our work thus demonstrates the potential of monatomic 2D PCRAM for the future development of high-performance neuromorphic computing chips.

Na0.5Bi0.5Ti0.98Mn0.02O3 (NBTMn) thin films were fabricated on indium tin oxide/glass substrates via chemical solution deposition and annealed at various temperatures from 450 to 600 °C and the influence of annealing temperature on their crystallization and electrical properties was investigated. X-ray diffraction measurement reveals that the film can be crystallized at an annealing temperature as low as 500 °C. The leakage current shows a decreasing tendency with a low and stable leakage current density of 10–7 A/cm2 as the annealing temperature increases to 550 °C. However, the electrical properties degrade at 600 °C, which may be due to the recrystallization effect together with ions volatilization. The NBTMn thin film annealed at 550 °C exhibits the higher ferroelectricity with a large remanent polarization (Pr) of 38 μC/cm2, which is nearly to the value of NBT ceramics.

Na0.5Bi0.5(Ti0.98Mn0.02)O3 (NBTMn) thin film was fabricated on fluorine-doped tin oxide (FTO)/glass substrate via a chemical solution decomposition method. The microstructure and electrical performances of NBTMn thin film were investigated. The XRD pattern reveals that the NBTMn thin film is crystallised into a phase-pure polycrystalline perovskite structure. Also the film possesses a homogeneous structure. Enhanced ferroelectricity is obtained with a large remnant polarisation (Pr) of 19.8 μC/cm2 reflected by polarisation–electric field (P–E) hysteresis loop, which is consistent with the typical butterfly-shaped capacitance–voltage (C–V) curve. At the optimum applied voltage of ±22 V, a maximum value of 27% for dielectric tunability is obtained. Additionally, the NBTMn thin film shows a dielectric constant of 422, dissipation factor of 0.06 and figure of merit of 4.5 at 100 kHz.