Hyperdoped silicon photodiode advances short-wave infrared detection at room temperature

Short-wave infrared (SWIR) light detection could significantly enhance various applications, from night vision and medical imaging to environmental monitoring and industrial inspection. Until now, most SWIR detectors have relied on costly semiconductors that struggle to integrate with existing electronics. However, researchers at Complutense University of Madrid have developed a silicon photodiode that efficiently absorbs SWIR light and is compatible with current manufacturing processes.

This groundbreaking device, detailed in a Physical Review Letters paper, is made by doping silicon with a high concentration of tellurium (Te) atoms, a process known as hyperdoping. It builds upon earlier efforts that encountered a performance ceiling due to the complexity of fabricating thin active layers. The team addressed this by decoupling the material's light absorption properties from its thickness through advanced light-trapping techniques, such as micro-texturing the silicon surface and adding a gold mirror.

By implanting Te atoms into the silicon lattice, the researchers created additional energy levels that allow low-energy SWIR photons to excite electrons and generate an electrical signal. This, combined with the micro-textured surface and rear gold mirror, maximizes light absorption within the hyperdoped layer. The photodiode is compatible with standard complementary metal-oxide-semiconductor (CMOS) manufacturing methods, making it potentially cost-effective and easily producible using existing industrial facilities.

In tests, the new SWIR-sensing photodiode achieved a specific detectivity of 4×10^10 Jones at room temperature and a wavelength of 1.5 micrometers, representing a record performance milestone for hyperdoped silicon. This high sensitivity, combined with the ability to operate efficiently at room temperature without cooling systems, demonstrates that high-sensitivity SWIR detection can be achieved using low-cost, mass-producible silicon technology.

The photodiode's performance outperformed all previously reported detectors based on silicon and hyperdoped materials for SWIR light detection. Future improvements and integration with other electronic components could create devices tailored for specific applications. If combined with cameras, this technology could potentially improve smartphones, tablets, and laptops by enhancing their night vision and facial recognition capabilities.

In the automotive industry, it could lead to safer vehicles by improving detection in adverse weather conditions like fog or low light. The researchers are currently developing a proof of concept for a SWIR image sensor based on this innovative silicon material.