Researchers at UC Berkeley of the University of California, USA, showcase the use of Si-CMOS optical lithography processes for three to five (III-V) nanocolumnar LED designs while also controlling the precise growth of these nanometers Is the effective integration of photons in the CMOS circuit, in order to achieve fast chip optical interconnect key elements.
"Ultracompact Position-Controlled InP Nanopillar LEDs on Silicon with Bright Electroluminescence at Telecommunication (" InP nanopillar LEDs on Silicon with Bright Electroluminescence at Telecommunication ") in the" ACS Photonics "Journal published in the journal" ACS Photonics " (InP) nanostructure arrays on silicon crystals can be grown on silicon-based conditions: low temperature and no catalyst, according to Wavelengths, which states that the yield growth rate is as high as 90%.
The position-controllable InP nanocolumnar array is grown at 460 ° C. The low magnification magnification SEM image shows that the scales in all images correspond to 10 μm and 1 μm, 4 μm and 40 μm growth periods (pitch)
The researchers first started from the clean silicon wafer (111), at 250 ℃ under 140nm of the oxide deposition to the diameter of about 320nm nano-aperture, the spacing of 1μm-40μm nano-column nucleation position. Researchers chemically make the surface of the silicon crystal rough, and then 450 ℃ ~ 460 ℃ temperature in the MOCVD cavity growth InP nanostructures. The researchers found that the cone angle of the nanocolumns was significantly affected by the growth temperature, producing nanosized needles at 450 ° C and almost vertical columnar structures at 460 ° C.
Based on these nanocolumns, the researchers incorporate five gallium arsenide indium (InGaAs) quantum wells into the active region of the pn diode through the core-core growth of the center, forming an electrically driven N-InP / InGaAs MQW / p-InP / p-InGaAs nano-LEDs.
Nano - pillar MQW LED assembly diagram
Due to the core-shell growth pattern, the nanocolumn grows out of its nucleation site and extends beyond the oxide opening to a final diameter of about 1 [mu] m. Thus, when the n-doped core of the nanocolumns is in direct contact with the n-Si substrate, the p-doped shell grows on the oxide shield, eliminating the shunt path from the p-doped shell and the n-Si substrate. 20/200 nm of Ti / Au is passed through the tilted electron beam to the highly p-doped InGaAs contact layer, completing the assembly to form an electrical contact in which a small portion of the nanocolumns are exposed and no metal is emitted as LED light window.
Characterized for nanoscale columnar LEDs at 1510 nm and about 30% quantum efficiency. Although the nano-column LED occupies a small footprint, but can output 4μW power, the researchers claimed that this is from the nano-pillar / nano-structure LED can achieve the highest light output records. Under this build, the available light output is reduced to 200nW due to the collection efficiency of only 5%.
Another interesting aspect of this study is that the component can generate optical gain with electrical bias and exhibit a strong light response during reverse implantation to help achieve photon integration on the chip.