HONG KONG, March 9, 2020 — Researchers from the Hong Kong University of Science and Technology (HKUST) have directly grown 1.5-μm III-V lasers on industry-standard 220-nm silicon-on-insulators (SOI) wafers without buffer. This work could advance the use of III-V light sources with silicon (Si)-based photonic devices.
In conventional approaches to integrating III-V lasers on Si, III-V buffers up to a few μm thick are applied to reduce the defect densities. The thickness of these buffers can make the interface between the III-V lasers and the Si-based waveguides less efficient. The HKUST team devised a growth scheme that eliminates the need for thick III-V buffers to allow more efficient light coupling into the Si-waveguides.
The group led by professor Lau Kei-May used metal organic chemical vapor deposition to grow the III-V lasers on SOI wafers. This approach featured epitaxy inside trapezoidal troughs to enable the flexible integration of different III-V compounds on SOIs with different Si device layer thicknesses. The researchers characterized the crystalline quality of these III-V materials through photoluminescence measurements and extensive use of transmission electron microscopy.