Xidian University Team Develops Cost-Effective SiGe SPAD Chip for Short-Wave Infrared Detection

Xi’an – Reporters learned from Xidian University on March 30 that a research team led by Professor Hu Huiyong from the university has successfully developed a Single-Photon Avalanche Diode (SPAD) chip based on silicon-germanium (SiGe) technology, significantly reducing the manufacturing cost of short-wave infrared detection technology. This breakthrough is expected to bring high-end chips, which once cost thousands of US dollars each, into fields such as smartphones and automotive lidar at one percent of the original cost, according to Global Network reports.

Short-wave infrared technology boasts the ability to penetrate haze, capture clear images in the dark and identify the material characteristics of different substances, boasting broad prospects in areas like low-light photography of smartphones, automotive lidar and industrial non-destructive testing. However, mainstream solutions have long relied on indium gallium arsenide (InGaAs) materials. Despite their excellent performance, they are limited by expensive indium phosphide (InP) substrates and incompatibility with silicon-based CMOS (Complementary Metal-Oxide-Semiconductor) processes, with a single chip costing hundreds to thousands of US dollars.

"It’s like building household appliances in the way of manufacturing space shuttles – the cost and scale are not on the same level," Wang Liming, a core member of the team, put it metaphorically.

Professor Hu Huiyong’s team chose a technical route highly compatible with the existing semiconductor industry chain – silicon-germanium. They completed material growth using a SiGe epitaxial process platform and then fabricated detection devices with a standard silicon-based CMOS process platform, extending the detection range to the short-wave infrared band. "This means we are manufacturing short-wave infrared detectors, which used to be ‘sky-high priced’, at the cost of making mobile phone chips," Wang Liming explained.

Nevertheless, there is a 4.2% lattice mismatch between the atomic arrangement periods of silicon and germanium. This misalignment leads to material defects and detector leakage, preventing the technology from moving out of laboratories for more than 20 years. To overcome this challenge, the team made efforts in multiple aspects: designing a multi-layer graded buffer layer combined with low-temperature growth technology to gradually reduce atomic-level mismatch; adopting in-situ annealing and passivation technologies to suppress leakage; and optimizing the electric field distribution through innovative SPAD structure design to achieve clearer signals and lower noise.

Currently, the team has built an independent full-chain R&D capability covering "device design – material epitaxy – process tape-out – circuit matching – system verification". A dedicated SiGe tape-out line under construction is expected to be completed by the end of 2026, providing rapid verification and controllable production capacity support for subsequent product iterations. This breakthrough not only fills the gap in cost-effective short-wave infrared detection chips in China but also paves the way for the popularization of related technologies in civilian and industrial fields.