Micro optical sensors based on avalanching silicon light-emitting devices monolithically integrated on chips

TLDR

Silicon avalanche light‑emitting devices (Si Av LEDs) emit 450–850 nm light at a few hundred nW µm⁻² and can be fabricated in micro‑ and nano‑dimensions using standard silicon processing, enabling on‑chip micro‑ and nano‑optical biosensors. The authors designed a micro‑fluidic channel sensor that exploits the dispersion properties of Si Av LEDs to detect analytes. The sensor interrogates analytes by measuring their transmittance and absorption spectra in the micro‑fluidic channel and, as simulations show, can be integrated with a waveguide‑based detector between the Si source and a Si P‑I‑N detector. Experiments revealed dispersion in the Si Av LED and localized emission about one micron below the Si/SiO₂ interface, while simulations confirm that the proposed waveguide‑based sensor can be fabricated on chip.

Abstract

Silicon avalanche light-emitting devices (Si Av LEDs) offer various possibilities for realizing micro- and even nano- optical biosensors directly on chip. The light-emitting devices (LEDs) operate in the wavelength range of about 450-850nm, and their optical power emitted is of the order of a few hundreds of nW/µm2. These LEDs could be fabricated in micro- and nano- dimensions by using modern semiconductor fabrication processing technologies through the mainstream of silicon material. Through a series of experiments, the dispersion phenomena in the Si Av LED are observed. Also, its light emission point was proved to locate at about one micron just below the silicon-silicon oxide interface. Subsequently, a micro-fluidic channel sensor was designed by using the dispersion characteristics owned by the Si Av LED. The analytes flowing through a micro-fluidic channel could be studied by their specific transmittance and absorption spectra. Moreover, simulations verify that a novel designed waveguide-based sensor could be fabricated on chip between the Si optical source and the Si P-I-N detector.