Scaling Laws for NanoFET Sensors

TL;DR

This paper investigates the scaling laws of nanoFET sensors using resistor network models, revealing how device size, shape, and field effect strength influence detection thresholds and sensitivities.

Contribution

It introduces a simplified resistor network model for nanoplate FET sensors and analyzes how scaling and field effects impact sensor sensitivity and detection limits.

Findings

Detection thresholds depend on field effect strength.

Sensor sensitivity transitions occur at specific size thresholds.

Design modifications can eliminate detection limits.

Abstract

The sensitive conductance change of semiconductor nanowires and carbon nanotubes in response to binding of charged molecules provide a novel sensing modality which is generally denoted as nanoFET sensors. In this paper, we study the scaling laws of nanoplate FET sensors by simplifying nanoplates as random resistor networks with molecular receptors sitting on lattice sites. Nanowire/tube FETs are included as the limiting cases where the device width goes small. Computer simulations show that the field effect strength exerted by the binding molecules has significant impact on the scaling behaviors. When the field effect strength is small, nanoFETs have little size and shape dependence. In contrast, when the field-effect strength becomes stronger, there exists a lower detection threshold for charge accumulation FETs and an upper detection threshold for charge depletion FET sensors. At these thresholds, the nanoFET devices undergo a transition between low and large sensitivities. These thresholds may set the detection limits of nanoFET sensors, while could be eliminated by designing devices with very short source-drain distance and large width.