Electron-Beam-Induced Negative Differential Transconductance Homojunction Device Based on van der Waals Materials for Functionally Complete Ternary Computing

Abstract

Negative differential transconductance (NDT) devices have emerged as promising candidates for multivalued logic computing, and particularly for ternary logic systems. To enable computation of any ternary operation, it is essential to have a functionally complete set of ternary logic gates, which remains unrealized with current NDT technologies, posing a critical limitation for higher-level circuit design. Additionally, NDT devices typically rely on heterojunctions, complicating fabrication and impacting reliability due to the introduction of additional materials and interfaces. Here, we utilize an electron beam to develop tungsten diselenide (WSe₂) homojunction NDT devices with W-shaped current–voltage (I–V) characteristics. We demonstrate that electron beam enables the manipulation of Se atoms in WSe₂, facilitating controllable and spatially precise tailoring of the WSe₂ work function. The electron-beam treatment applied to a part of the WSe₂ channel induces a lateral homojunction and ultimately results in the W-shaped I–V curves, which enable both one-input and two-input ternary logic gates. We propose and implement a balanced circuit design for two-input ternary NAND, AND, NOR, and OR gates, featuring a low device count, full-swing operation, and minimized output signal variations. Together with three types of ternary inverters also designed in this work, they form a functionally complete set of ternary logic gates─a prerequisite for practical ternary computing. This work addresses a critical gap in the development of NDT-based ternary computing by ensuring functional completeness and highlights the versatility of electron-beam treatment as an engineering tool for tailoring the properties of two-dimensional van der Waals materials.