Physical Insights into Vacancy-Based Memtransistors: Toward Power Efficiency, Reliable Operation, and Scalability

Abstract

Memtransistors that combine the properties of transistor and memristor hold significant promise for in-memory computing. While superior data storage capability is achieved in memtransistors through gate voltage-induced conductance modulation, the lateral device configuration would not only result in high write bias, which compromises the power efficiency, but also suffers from unsuccessful memory reset that leads to reliability concerns. To circumvent such performance limitations, an advanced physics-based model is required to uncover the dynamic resistive switching behavior and deduce the key driving parameters for the switching process. This work demonstrates a self-consistent physics-based model which incorporates the often-overlooked effects of lattice temperature, vacancy dynamics, and channel electrostatics to accurately solve the interaction between gate potential, ions, and carriers on the memristive switching mechanism. The completed model is carefully calibrated with an ambipolar WSe2 memtransistor and hence enables the investigation of the carrier polarity effect (electrons vs holes) on vacancy transport. Nevertheless, the validity of the model can be extended to different materials by a simple material-dependent parameter modification. Building upon the existing understanding of Schottky barrier height modulation, our study reveals three key insightsleveraging threshold voltage shifts to lower write bias; optimizing lattice temperature distribution and read bias polarity to achieve successful memory state recovery; engineering contact work function to overcome the detrimental parasitic current flow in short channel ambipolar memtransistors. Therefore, understanding the significant correlation between the switching mechanisms, different material systems, and device structures allows performance optimization of operating modes and device designs for future memtransistors-based computing systems.

Se-Vacancy Healing with Substitutional Oxygen in WSe2 for High-Mobility p-Type Field-Effect Transistors

“…The decrease in the binding energy of the W 4f doublet can be attributed to the presence of O in the WO x form. 8 The locally occupied O ions at Se locations give rise to W−O bonds that affect the transport of charge carriers and move the Fermi level toward the valence band edge. 8,12 For further insights, the low-resolution depth profiling of all elements was analyzed.…”

“…8 The locally occupied O ions at Se locations give rise to W−O bonds that affect the transport of charge carriers and move the Fermi level toward the valence band edge. 8,12 For further insights, the low-resolution depth profiling of all elements was analyzed. The variation in atomic concentration (atom %) of elements is plotted against the etching time in Figure 2a.…”

“…12 WSe 2 oxidation surface treatment was performed using a remote plasma oxidation technique to effectively enhance hole mobility while transferring electrons from WSe 2 to WO 3 . 8 From a practical perspective, surface treatment contains a flaw in the principle that mobility improvement may not be continuous for a sustained period.…”

“…Previous studies have shown that the presence of W−O in the continuous covalent network of W−Se controls the charge concentration and enhances its electrical functionality. 8,13,17 In the present work, a solution-derived transparent conducting oxide (TCO), that is, aluminum-doped zinc oxide (AZO), was utilized as the source of oxygen for WSe 2 . The heterostructural architecture of mechanically exfoliated WSe 2 and solution-cast AZO (WSe 2 /AZO) was utilized for the compositional alteration of WSe 2 .…”

N‐P Reconfigurable Dual‐Mode Memtransistors for Compact Bio‐Inspired Feature Extractor with Inhibitory‐Excitatory Spiking Capability

“…A similar plot of the distribution of Se vacancies (Figure S9a, Supporting Information) and band diagram (Figure S9b, Supporting Information) for beginning of paths 3 and end of 4 is shown in Section S9 (Supporting Information). Notably, the larger degree of Joule heating in paths 3 and 4 under a higher current accelerates the migration of chalcogen vacancies [41,44] which has led to a greater change in conductance state compared to paths 1 to path 2. Hence, we have explained the quantitative V th shifts that results from the space charge effect due to positively-charged electron-donor-like Se vacancies and verified the unique physics of the MS in such the memtransistor.…”