[China Instrument Network Instrument Research and Development] Silicon is the most common material in the semiconductor industry. Silicon-based electronic chips are widely used in various devices in daily life, from smart phones and computers to automobiles, aircraft, and satellites. With the development of technology, researchers have found that the communication between the chip and the system through the traditional electrical interconnection has been difficult to meet the faster communication speed between electronic devices and the requirements of more complex systems.
To solve this problem, "light" is considered as a very high-speed ultra-high-speed transmission medium for silicon-based chips and data communication between systems. However, silicon, as an indirect bandgap material, has extremely low luminous efficiency and is difficult to directly use as a luminescent material. The researchers proposed the use of a group III-V material with high luminous efficiency as a luminescent material, grown or bonded on a silicon substrate to achieve silicon-based optoelectronic integration.
The III-nitride material is a kind of direct bandgap material, which has the advantages of wide band gap, high chemical stability, high breakdown electric field and high thermal conductivity, and has wide application prospects in high-efficiency light-emitting devices and power electronic devices. In recent years, it has become a major research hotspot. InGaN-based lasers are grown directly on silicon substrate materials, providing the possibility of organic integration of GaN-based optoelectronic devices and silicon-based optoelectronic devices. On the other hand, since its introduction in 1996, InGaN-based lasers have developed rapidly in more than 20 years, and their applications range from information storage, lighting, laser display, visible light communications, submarine communications, and biomedical applications.
At present, almost all InGaN-based lasers are fabricated using expensive self-supporting GaN substrates, which limits their application. The silicon substrate has the advantages of low cost, high thermal conductivity, and large wafer size. If an InGaN-based laser can be fabricated on a silicon substrate, it will effectively reduce its production cost and further promote its application.
Due to the large lattice constant mismatch and thermal expansion mismatch between the GaN material and the silicon substrate, directly growing the GaN material on the silicon substrate causes the GaN film to have a high dislocation density and is prone to cracks. InGaN-based lasers are difficult to prepare. The research direction is currently a research hotspot in the world, but so far only the article has reported the lasing of the InGaN-based multi-quantum well light-emitting structure on a silicon substrate under optical pumping conditions.
In response to this key scientific and technological problem, the group III nitride semiconductor material and device research team led by researcher Yang Hui of the Suzhou Institute of Nanotechnology and Nano-Bionics, Chinese Academy of Sciences, used an AlN/AlGaN buffer layer structure to effectively reduce the dislocation density while succeeding The cracks often caused by the thermal expansion coefficient mismatch between silicon and GaN materials are suppressed, and an InGaN-based laser structure with a thickness of about 6 μm is successfully grown on the silicon substrate, and the dislocation density is less than 6×108 cm-2. Through the device process, the world's first silicon-on-insulator InGaN laser with lasing at room temperature was successfully realized. The lasing wavelength was 413 nm, and the threshold current density was 4.7 kA/cm2.
The project was supported by the Frontier Science and Education Bureau of the Chinese Academy of Sciences, the pilot project of the Chinese Academy of Sciences, the National Natural Science Foundation of China, the Ministry of Science and Technology's key research and development program, and the self-funded funding of the Suzhou Nanotechnical Institute of the Chinese Academy of Sciences. The Suzhou Nanometer Institute’s processing platform, test platform, and Nano-X provided Technical Support. The relevant research results were published online on August 15 in the international academic journal Nature Photonics.
(Original title: Suzhou Nano has made progress in the research of silicon-based InGaN-based semiconductor lasers)