Transparent conductive oxides and low-loss nitride-rich silicon waveguides as building blocks for neuromorphic photonics

Abstract

Fully CMOS-compatible photonic memory holding devices hold a potential in the development of ultrafast artificial neural networks. Leveraging the benefits of photonics such as high-bandwidth, low latencies, low-energy interconnect, and high speed, they can overcome the existing limits of electronic processing. To satisfy all these requirements, a photonic platform is proposed that combines low-loss nitride-rich silicon as a guide and low-loss transparent conductive oxides as an active material that can provide high nonlinearity and bistability under both electrical and optical signals.

Schottky Photodetectors with Transparent Conductive Oxides for Photonic Integrated Circuits

“…This results in nearly a 10-fold increase in the field strength, which corresponds to a remarkable 100-fold enhancement in energy density. The process of field enhancement in the thin layer of the TCO material arranged in the photonics and plasmonic waveguide structure was in detail described in our previous papers in refs 25,26. It is worth highlighting that the real part of the effective index experiences a marginal change of just 0.2%.…”

“…In a typical TCO, the situation is different, as shown in Figure (b). The Fermi level is relatively small, about 0.65 eV for the AZO operating near ENZ point with carrier concentration of N c ∼ 7 × 10 26 m –3 . − Since ℏω > E F the carriers are excited from the filled states with − E F < E < 0 where the density of states is nonuniform. Therefore, excited states energy distribution ℏω – E F < E < ℏω maintains (until electron–electron (EE) scattering causes redistribution of “hot” carriers) the same parabolic distribution in the band with more carriers having energies above the barrier than in the case of metal with the same value of the energy barrier.…”

“…Here, we propose substituting metal with a transparent conductive oxide (TCO) material, − using aluminum zinc oxide (AZO) , as an illustrative example. We focus on the ZnO-based compound as it is biocompatible, biodegradable, biosecure, cheap, and CMOS-compatible (as other TCO materials) and is already considered for sensing and optoelectronic and storage applications. , However, the family of transparent conductive oxides (TCOs) is very broad ranging from indium tin oxide (ITO), indium zinc oxide (IZO), cadmium oxide (CdO), gallium zinc oxide (GZO), and aluminum zinc oxide (AZO) to mention only a few of the most popular compounds .…”

Integrated Bolometric Photodetectors Based on Transparent Conductive Oxides from Near‐ to Mid‐Infrared Wavelengths

“…Transparent conductive oxides (TCOs), which belong to the epsilon‐near‐zero (ENZ) materials, seem to be an excellent material for such a task, as they can absorb energy under a wide range of wavelengths. [ 15–20 ] They possess large permittivity tunability under an applied voltage or light illumination, [ 21–26 ] allowing the material properties to be tuned to specific requirements. They also feature low optical loss, fast switching time, and low switching voltage.…”

“…of wavelengths. [15][16][17][18][19][20] They possess large permittivity tunability under an applied voltage or light illumination, [21][22][23][24][25][26] allowing the material properties to be tuned to specific requirements. They also feature low optical loss, fast switching time, and low switching voltage.…”