An integrated capacitance bridge for high-resolution, wide temperature range quantum capacitance measurements

TL;DR

This paper introduces a highly-sensitive integrated capacitance bridge utilizing a GaAs HEMT amplifier, achieving attofarad resolution across 4K to 300K, significantly surpassing commercial devices in quantum capacitance measurements of graphene.

Contribution

The paper presents a novel integrated capacitance bridge with unprecedented resolution for quantum capacitance measurements over a wide temperature range.

Findings

Achieved 10aF/√Hz resolution at room temperature.

Demonstrated superior performance compared to commercial capacitance bridges.

Successfully measured quantum capacitance of top-gated graphene devices.

Abstract

We have developed a highly-sensitive integrated capacitance bridge for quantum capacitance measurements. Our bridge, based on a GaAs HEMT amplifier, delivers attofarad (aF) resolution using a small AC excitation at or below kT over a broad temperature range (4K-300K). We have achieved a resolution at room temperature of 10aF per root Hz for a 10mV AC excitation at 17.5 kHz, with improved resolution at cryogenic temperatures, for the same excitation amplitude. We demonstrate the performance of our capacitance bridge by measuring the quantum capacitance of top-gated graphene devices and comparing against results obtained with the highest resolution commercially-available capacitance measurement bridge. Under identical test conditions, our bridge exceeds the resolution of the commercial tool by up to several orders of magnitude.