New design paradigm for highly efficient and low noise photodetector

TL;DR

This paper introduces a novel photodetector design that uses dielectric Mie resonance to achieve high absorption in ultrathin layers, significantly reducing dark current and noise while maintaining high quantum efficiency.

Contribution

The authors propose a new design paradigm leveraging dielectric Mie resonance coupling to enhance light absorption in ultrathin photodetectors, enabling high efficiency and low noise performance.

Findings

Achieves ~90% absorption in <100 nm layers

Reduces dark current by at least two orders of magnitude

Potential for large optical gain through avalanche process

Abstract

Achieving high quantum efficiency (QE) with low dark count is essential for highly sensitive photodetectors (PDs), including single photon avalanche detectors (SPADs). However, high QE requires a thicker absorber region, which leads to high dark current and noise, which in turn affects the detectivity of PDs and the photodetection efficiency and dark count of SPADs.The holy grail of photodetector and avalanche photodiode designs is to achieve highest QE with thinnest absorber and still enable large avalanche to gain as needed. We have developed a new design paradigm which exploits the coupling between dielectric Mie resonance and transverse propagating waves in thin layers. The Mie resonance launches the incident light at an angle in an ultrathin absorber, and when coupled to transverse waves, the light propagates laterally and is fully absorbed owing to the longer optical path. Consequently, with appropriate choice of materials for a chosen wavelength, a high absorption(~90%) within typically <100 nm absorber thickness is possible. For illustration, we apply our approach to design Si-based detector operating at 810 nm and InGaAs-based detector operating at 1550 nm and predict that the dark current at room temperature is reduced at least by two orders of magnitude. In addition, the lateral distances are often in a few microns and hence these designs can potentially enable avalanching for a large optical gain.