Mid-infrared avalanche photodiode with hole-initiated multiplication.

Background

There is a growing demand for highly sensitive, low-noise photodetectors that can operate in the mid-infrared range for applications such as quantum sensing, secure communication, greenhouse gas monitoring, LiDAR, thermal imaging, and biosensing. Current detector technologies, such as HgCdTe and InAsSb photodiodes, are limited by high dark current, excess noise, low gain stability, and expensive or complex fabrication, making them inefficient for scalable imaging arrays and single photon-level sensing.

Technology

This technology introduces an advanced avalanche photodiode (APD) architecture specifically designed to achieve low-noise, high-gain performance in the mid-infrared region. The device uses a separated absorption and multiplication structure, which allows the electric field to be precisely controlled within the photodiode. By preventing high fields from entering the light-absorbing region, the design significantly reduces common noise sources, particularly those that arise from unwanted carrier generation in conventional mid-IR detectors. A key distinguishing feature of this APD is its use of a multiplication mechanism optimized to minimize excess noise, enabling more stable gain and more reliable signal extraction at extremely low light levels. This results in improved sensitivity for applications requiring single-photon or near single-photon detection. The detector is fabricated on a platform compatible with established semiconductor processing and is designed to support scalable implementation for imaging arrays or cryogenic operation.

Advantages

Suppressed tunneling dark current for low-noise detection
Enhanced gain through hole-initiated impact ionization mechanism
High responsivity in the mid-infrared spectral range
Scalable fabrication with high yield on GaSb substrates
Compatible with focal plane array integration

Application

Quantum biosensing for enhanced molecular detection
Secure optical communication systems requiring sensitive detectors
Autonomous vehicle sensing technologies in the mid-infrared spectrum
Advanced imaging and environmental monitoring systems