Terahertz microresonators for material characterisation

TL;DR

This paper investigates silicon THz microresonators, demonstrating that their quality factor depends linearly on substrate resistivity, enabling precise material absorption measurements in the THz range.

Contribution

The study systematically analyzes how substrate resistivity affects the Q-factor of silicon THz microresonators, providing a new methodology for material absorption characterization.

Findings

Q-factor increases linearly with resistivity from 10kΩcm to 15kΩcm

Material absorption is inversely proportional to resistivity

Method enables precise low-loss material measurements in THz domain

Abstract

Terahertz (THz) technology is rapidly evolving, and the advancement of data and information processing devices is essential. Silicon THz microresonators provide perfect platforms to develop compact and integrated devices that could transform THz technology. Here we present a systematic study on the key figure of merit of silicon THz disc microresonators - the quality factor (Q-factor) - in dependence on the substrate's resistivity. Our results show that the Q-factor depends linearly on the resistivity and a variation in resistivity from 10k$\Omega$cm to 15k$\Omega$cm changes the Q-factor from 50k to 76k at 0.6THz. Moreover, we experimentally determine that the silicon material absorption is inversely proportional to the substrate's resistivity. In general, the presented methodology is ideally suited to precisely measure the material absorption of low-loss materials in the THz domain, which is challenging using conventional THz spectroscopy.