CMOS-compatible titanium nitride for on-chip plasmonic Schottky photodetector

TL;DR

This paper explores titanium nitride as a CMOS-compatible plasmonic material for on-chip silicon Schottky photodetectors, demonstrating high efficiency and integration potential at telecom wavelengths.

Contribution

It introduces TiN as a novel plasmonic material with a suitable Schottky barrier height for silicon photodetectors, enhancing performance and CMOS compatibility.

Findings

TiN has a Schottky barrier height of 0.67 eV on p-doped silicon.

TiN enables high signal-to-noise ratio at 1550 nm.

TiN improves electron transmission due to shorter mode penetration depth.

Abstract

Here, we propose titanium nitride (TiN) as an alternative plasmonic material for an on-chip silicon plasmonic Schottky photodetector that is based on an internal photoemission process and operating at telecom wavelengths. The examined structure employs an asymmetric metal-semiconductor-metal waveguide structure with one of the electrodes being gold and the second either gold, titanium or titanium nitride. Apart from the excellent optical properties desired for this type of photodetector such as high absorption losses and reasonably high real part of the permittivity, titanium nitride is a CMOS-compatible material that enables easy integration with existing CMOS technology. For the first time, we find a Schottky barrier height of 0.67 eV for titanium nitride on p-doped silicon, which is very close to the optimal value of 0.69 eV. This value ensures very high signal-to-noise ratio of the photodetector operating at a wavelength of 1550 nm. Additionally, TiN provides shorter penetration depth of the mode into metal compared to Ti, which enhances transmission probability of hot electrons to a semiconductor and gives rise to responsivity enhancement.