Ultra-shallow junction electrodes in low-loss silicon micro-ring resonators

TL;DR

This paper demonstrates the integration of ultra-shallow, low-loss metallic electrodes into silicon micro-ring resonators, enabling combined optical and electronic functionalities with minimal impact on optical quality.

Contribution

It introduces a method to embed shallow phosphorus-doped metallic layers in silicon micro-rings that maintain high optical quality at cryogenic temperatures.

Findings

Achieved quality factors up to 10^5 with shallow doping

Demonstrated minimal optical losses from the metallic layer

Enabled potential integration of electronic devices with optical circuits

Abstract

Electrodes in close proximity to an active area of a device are required for sufficient electrical control. The integration of such electrodes into optical devices can be challenging since low optical losses must be retained to realise high quality operation. Here, we demonstrate that it is possible to place a metallic shallow phosphorus doped layer in a silicon micro-ring cavity that can function at cryogenic temperatures. We verify that the shallow doping layer affects the local refractive index while inducing minimal losses with quality factors up to 10$^5$. This demonstration opens up a pathway to the integration of an electronic device, such as a single-electron transistor, into an optical circuit on the same material platform.