The PhotoGeNIC consortium was born to introduce Ge substrates to the VCSEL (vertical-cavity surface-emitting lasers) manufacturing process. The project addresses the design, fabrication, and implementation of a novel VCSEL epi-structure grown on germanium (Ge) substrates instead of traditional gallium arsenide (GaAs). VCSELs are widely used in photonics, including short-distance communication systems, LIDARs, time-of-flight sensors, autonomous vehicles, robots, and drones. The project aims to develop new VCSEL industrial technology by applying Ge large diameter substrates, enhancing VCSEL quality in terms of cost efficiency, production yield, and environmental impact, and making a path for its integration with CMOS technology.
Photonics plays an essential role in driving innovation across many fields. Its applications span several sectors, from optical data communications, imaging, lighting, and displays through the manufacturing sector to life sciences, health care, security, and safety. Photonics offers new and unique solutions where today's conventional technologies are approaching their limits in terms of speed, capacity, and accuracy. The impact of photonics has been recognized as one of Europe's key enabling technologies (KETs) of the 21st century.
To date, VCSELs are the most miniature commercial coherent light sources offering narrow spectral width emission, low threshold current, high modulation speed, and relatively simple device fabrication. The VCSEL structure consists of a Fabry-Perot cavity (resonator), an active region with several quantum wells, where light is generated, and top and bottom DBRs (Distributed Bragg Reflector). DBR comprises a stack of semiconductor layers (each with a thickness of a quarter of the laser wavelength) that reflect a particular range of light wavelengths.
Today, one of the key challenges in developing VCSEL is the improvement of its spectral characteristics, optical power, reliability, and the reduction of production costs, including the type, size, and thickness of applied substrates. The project proposes an innovative solution, using Ge substrates instead of traditional GaAs substrates.
One of the project's main objectives is mastering the epitaxial growth development of VCSEL epi-stack on Ge large substrates and processing development of high-performance and reliable lasers to be integrated with 3D cameras and LiDAR demonstrators. The expected results include large wafers with improved quality, better uniformity, and lower defect densities produced using a more environment-friendly solution.
