Visible and near-infrared responsivity of femtosecond-laser microstructured silicon photodiodes

TLDR

Responsivity of silicon photodiodes depends on substrate doping, microstructuring fluence, and annealing temperature. The study investigated the current–voltage characteristics and responsivity of photodiodes fabricated by femtosecond‑laser microstructuring of silicon in a sulfur‑containing atmosphere. Photodiodes were fabricated by microstructuring silicon with femtosecond‑laser pulses in a sulfur‑containing atmosphere and characterized by current–voltage measurements. The devices show a broad spectral response from 400 to 1600 nm, achieving room‑temperature responsivities up to 100 A W⁻¹ at 1064 nm—two orders of magnitude higher than standard silicon photodiodes—and up to 50 mA W⁻¹ at 1330 nm and 35 mA W⁻¹ at 1550 nm for sub‑bandgap wavelengths.

Abstract

We investigated the current–voltage characteristics and responsivity of photodiodes fabricated with silicon that was microstructured by use of femtosecond-laser pulses in a sulfur-containing atmosphere. The photodiodes that we fabricated have a broad spectral response ranging from the visible to the near infrared (400–1600?nm). The responsivity depends on substrate doping, microstructuring fluence, and annealing temperature. We obtained room-temperature responsivities as high as 100?A?W at 1064?nm, 2 orders of magnitude higher than for standard silicon photodiodes. For wavelengths below the bandgap we obtained responsivities as high as 50?mA?W at 1330?nm and 35?mA?W at 1550?nm.