Ultrafast-programmable two-dimensional homojunctions based on van der Waals heterostructures on a silicon substrate.

The development of electrically ultrafast-programmable semiconductor homojunctions can lead to transformative multifunctional electronic devices. However, silicon-based homojunctions are not programmable so that alternative materials need to be explored. Here we demonstrate two-dimensional (2D), multi-functional, lateral homojunctions made of van der Waals heterostructures with a semi-floating-gate configuration on a p ++ Si substrate feature atomically sharp interfaces and can be electrostatically programmed in nanoseconds, more than seven orders of magnitude faster than other 2D-based homojunctions. By applying voltage pulses with different polarities, lateral p-n, n + -n and other types of homojunctions can be formed, varied, and reversed. The p-n homojunctions possess a high rectification ratio up to ∼10 5 and can be dynamically switched between four distinct conduction states with the current spanning over nine orders of magnitude, enabling them to function as logic rectifiers, memories and multi-valued logic inverters. Built on a p ++ Si substrate, which acts as the control gate, the devices are compatible with Si technology. This article is protected by copyright. All rights reserved.