Many optoelectronic devices embedded in a silicon photonic chip, like photodetectors, modulators and attenuators, rely on waveguide doping for their operation. However, the doping level of a waveguide is not always reflecting in an equal amount of free carriers available for conduction, because of the charges and trap energy states inevitably present at the Si/SiO2 interface. In a Silicon-On-Insulator technology with 10^15 cm-3 p-doped native waveguides this can lead to a complete depletion of the core from free carriers and to a consequent very high electrical resistance. This letter experimentally quantifies this effect and shows how the amount of free carriers in a waveguide can be modified and restored to the original doping value with a proper control of the chip substrate potential. A similar capability is also demonstrated by means of a specific metal gate integrated above the waveguide, that allows fine control of the conductance with high locality level. The paper highlights the linearity achievable in the conductance modulation, that can be exploited in a number of possible applications.

Electrical conductance of silicon photonic waveguides

Zanetto, Francesco;Perino, Alessandro;Petrini, Matteo;Toso, Fabio;Milanizadeh, Maziyar;Morichetti, Francesco;Melloni, Andrea;Ferrari, Giorgio;Sampietro, Marco
2021

Abstract

Many optoelectronic devices embedded in a silicon photonic chip, like photodetectors, modulators and attenuators, rely on waveguide doping for their operation. However, the doping level of a waveguide is not always reflecting in an equal amount of free carriers available for conduction, because of the charges and trap energy states inevitably present at the Si/SiO2 interface. In a Silicon-On-Insulator technology with 10^15 cm-3 p-doped native waveguides this can lead to a complete depletion of the core from free carriers and to a consequent very high electrical resistance. This letter experimentally quantifies this effect and shows how the amount of free carriers in a waveguide can be modified and restored to the original doping value with a proper control of the chip substrate potential. A similar capability is also demonstrated by means of a specific metal gate integrated above the waveguide, that allows fine control of the conductance with high locality level. The paper highlights the linearity achievable in the conductance modulation, that can be exploited in a number of possible applications.
OPTICS LETTERS
Integrated photonics, silicon photonics, optical waveguides, sensors
File in questo prodotto:
File Dimensione Formato  
Electrical Conductance of Silicon Photonic Waveguides_revised_reduced.pdf

embargo fino al 01/01/2022

Descrizione: post-print
: Post-Print (DRAFT o Author’s Accepted Manuscript-AAM)
Dimensione 613.12 kB
Formato Adobe PDF
613.12 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/1167147
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 2
  • ???jsp.display-item.citation.isi??? 2
social impact