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In this paper, the switching variability of SiNx-based RRAM with reactive metal electrodes in terms of Joule heating dissipation was analyzed. The electrode with high (low) thermal conductivity showed low LRS (HRS) variability in SiNx-based RRAM. By analyzing the I–V characteristics and the current conduction mechanism, we proposed that the thermal conductivity of reactive electrodes significantly affected the number of ions involved in the switching process and the vacancies distribution in the switching layer, resulting in the difference in the switching performance. This study suggested that attention should be paid to the influence of electrode thermal conductivity on variability, providing ideas for designing RRAM with low switching variability. [ABSTRACT FROM AUTHOR]

Doping engineering is crucial for both fundamental science and emerging applications. While transition metal (TM) dopants exhibit considerable advantages in the tuning of magnetism and conductivity in bulk Ga2O3, investigations on TM-doped two-dimensional (2D) Ga2O3 are scarce, both theoretically and experimentally. In this study, the detailed variations in impurity levels within 3d TM-doped 2D Ga2O3 systems have been explored via first-principles calculations using the generalized gradient approximation (GGA) +U method. Our results show that the Co impurity tends to incorporate on the tetrahedral GaII site, while the other dopants favor square pyramidal GaI sites in 2D Ga2O3. Moreover, Sc3+, Ti4+, V4+, Cr3+, Mn3+, Fe3+, Co3+, Ni3+, Cu2+, and Zn2+ are the energetically favorable charge states. Importantly, a transition from n-type to p-type conductivity occurs at the threshold Cu element as determined by the defect formation energies and partial density of states (PDOS), which can be ascribed to the shift from electron doping to hole doping with respect to the increase in the atomic number in the 3d TM group. Moreover, the spin configurations in the presence of the square pyramidal and tetrahedral coordinated crystal field effects are investigated in detail, and a transition from high-spin to low-spin arrangement is observed. As the atomic number of the 3d TM dopant increases, the percentage contribution of O ions to the total magnetic moment significantly increases due to the electronegativity effect. Additionally, the formed 3d bands for most TM dopants are located near the Fermi level, which can be of significant benefit to the transformation of the absorbing region from ultraviolet to visible/infrared light. Our results provide theoretical guidance for designing 2D Ga2O3 towards optoelectronic and spintronic applications. [ABSTRACT FROM AUTHOR]

Nowadays there is considerable interest in the photogalvanic effect in low-dimensional devices. In this work, we built a two-dimensional Bi2C-based photodetector and explored the spin-dependent photogalvanic effect under linearly polarized light and zero-bias conditions which can produce experimentally observable photoelectron flow. It was discovered that by introducing vacancies and substitution-doping into the Bi2C photodetector, the photogalvanic effect could be enhanced by 10–100 times that of a pristine photodetector, which is sufficient to be detected in experiments. Moreover, due to strong spin–orbit interactions, the Bi2C photodetector can produce very high spin polarization, even 100% full spin polarization, and pure spin current at a specific incident angle and photon energy, for example in the Bi1-vacancy Bi2C photodetector. In addition, the photon energy of incident light can regulate the produced spin photocurrent, which shows considerable anisotropy. Our results highlight the potential of the Bi2C photodetector as a versatile device in optoelectronics and spintronics applications. [ABSTRACT FROM AUTHOR]

Herein, a digital–analog hybrid resistive random‐access memory (RRAM) is prepared by integrating the structurally similar SiNx‐based digital‐type RRAM with analog‐type RRAM by heterogeneous integration method. The Pt/SiNx/Ta/Ru is a digital RRAM due to the formation and breakage of the internal silicon dangling bonds conductive filaments, and the TiN/SiNx/Ta/Ru structure is an analog RRAM due to the traps‐filled limit region of the space‐charge limited current. The heterogeneously integrated digital RRAM has good cycling stability and endurance characteristics, and the heterogeneously integrated analog RRAM has high linearity and multistate counting characteristics. This heterogeneous integration approach is useful for the implementation of hybrid digital–analog RRAM. [ABSTRACT FROM AUTHOR]

The photogalvanic effects (PGEs) in low-dimensional devices have attracted great interests recently. Herein, based on non-equilibrium Green's function combined with density functional theory, we investigated spin-dependent PGE phenomena in the BiC photodetector with the linearly polarized light and zero bias. Due to the presence of strong spin–orbit interaction (SOI) and C 3 v symmetry for the BiC monolayer, the armchair and zigzag BiC photodetectors can produce robust spin-dependent PGEs which possess the cos(2 θ) and sin(2 θ) relations on the photon energies, respectively. Especially, the pristine armchair and armchair Bi-vacancy BiC photodetectors can produce fully spin polarization, and pure spin current was found in the pristine armchair and zigzag BiC photodetector, respectively. Furthermore, after introducing the Bi-vacancy, C-vacancy, Bi-doping and C-doping respectively, the BiC photodetector can produce higher spin-dependent PGEs for their C s symmetry. Additionally, the behaviors of spin-dependent photoresponse are highly anisotropic which can be tuned by the photon energy. This work suggested great potential applications of the BiC monolayer on PGE-driven photodetectors in low energy-consumption optoelectronics and spintronic devices. [ABSTRACT FROM AUTHOR]

Herein, the effect of temperature on the switching characteristics and the conduction mechanism of the Ti/SiNx/Pt resistive random access memory device is investigated. The switching behavior of the device is investigated by comparing the I–V curves of the device in the temperature range of RT‐653 K. The temperature dependence of the current and the conduction mechanism of the device within RT‐463 K is investigated. It is found that the device exhibits good bipolar switching behavior in the temperature range of RT‐463 K, and the low resistance state (LRS) current and high resistance state (HRS) current show an increasing and then decreasing trend with increasing temperature. There is a stronger temperature dependence of the LRS current and the conduction mechanism from ohmic conduction to Schottky emission under LRS, which is attributed to the involvement of the reactive electrode Ti in the reaction at a certain temperature and the generation of a TiNx layer. Based on the above phenomenon, it is believed that not only the temperature affects the reliability of the device, but also the influence of reactive electrodes cannot be ignored. This article provides a reference for further preparation of SiNx‐based resistive random access memory devices with higher reliability and wider temperature usage range. [ABSTRACT FROM AUTHOR]

This Letter is about the role of the bottom electrode in the resistive switching of SiNx-based resistive random-access memory. Titanium nitride (TiN) and platinum (Pt) are used as bottom electrodes to fabricate devices whose I–V characteristics are compared. The devices with Pt as the bottom electrode have digital resistive switching behavior with a main memory window. However, the devices with TiN as the bottom electrode provide an analog resistive switching with the gradual operation. We propose that this switching difference is due to the different work functions of the top and bottom electrodes and the nitrogen-rich layer formed at the SiNx/TiN interface. The work function of the bottom electrode is larger than the top electrode in the device with Pt electrodes, which are considered non-reactive. However, the difference in the work functions between the bottom and top electrodes is not much for the device with a TiN electrode. As the nitrogen-rich layer formed at the SiNx/TiN interface has nitrogen accommodation ability, the nitrogen ions are more likely to drift to the bottom electrode, and resistive switching changes from digital to analog for the device with TiN electrodes. [ABSTRACT FROM AUTHOR]