Multifunctional Devices and Logic Gates With Undoped Silicon Nanowires

TL;DR

This paper demonstrates the fabrication and control of undoped silicon nanowire devices with multiple functionalities, including transistors and diodes, enabling reconfigurable logic gates such as NAND with high gain.

Contribution

It introduces a method to independently tune contact and channel properties in undoped silicon nanowires, achieving reconfigurable device functionalities and logic gate implementation.

Findings

Effective suppression of Schottky barriers using wrap gates

Reconfigurable device functionalities (transistor, diode, p-n diode)

NAND logic gate with gain above one

Abstract

We report on the electronic transport properties of multiple-gate devices fabricated from undoped silicon nanowires. Understanding and control of the relevant transport mechanisms was achieved by means of local electrostatic gating and temperature dependent measurements. The roles of the source/drain contacts and of the silicon channel could be independently evaluated and tuned. Wrap gates surrounding the silicide-silicon contact interfaces were proved to be effective in inducing a full suppression of the contact Schottky barriers, thereby enabling carrier injection down to liquid-helium temperature. By independently tuning the effective Schottky barrier heights, a variety of reconfigurable device functionalities could be obtained. In particular, the same nanowire device could be configured to work as a Schottky barrier transistor, a Schottky diode or a p-n diode with tunable polarities. This versatility was eventually exploited to realize a NAND logic gate with gain well above one.