Si-CMOS - compatible nanoscale LED can make photons more accurate

Researchers at the University of California at Berkeley (UC Berkeley) show the design of 35 (III-V) nanoscale LED with compatible Si-CMOS optical microphotography, and can also control the exact location of these nanoscale LED, which is the key to the efficient integration of photons in CMOS circuits to achieve fast chip optical interconnection. Elements.

Researchers in the Journal ACS Photonics published "InP nanoscale LED" (Ultracompact Position-Controlled InP Nanopillar LEDs on Silicon with). The yield of the control growth position is up to 90%, and the uniform indium phosphide (InP) nanoscale array can be realized on the silicon crystal. It is grown under the CMOS compatible condition: low temperature and no catalyst.

The position controllable InP nanometers array at 460 degrees centigrade enlargement of the low magnification SEM map the scale of all images corresponds to 10 m and 1 mu m, 4 mu m and 40 mu m growth period (spacing).

The researchers first started from a clean silicon wafer (111) and deposited two of the 140nm into a nanoscale diameter of about 320nm at 350 centigrade. The nucleation position of the nanoscale column was located at the distance between 1 mu M-40 and M. After the researchers made the silicon crystal surface rough by chemical method, the InP nanostructures were grown in the MOCVD cavity at the temperature of 450 to 460. The researchers found that the cone angle of the nanometers was obviously affected by the growth temperature, and the nanowires were produced at 450 C, and the vertical columnar structure was almost vertical at 460.

On the basis of these nanoscale, the researchers grew through the core core shell (core-shell) and incorporated five GaAs (InGaAs) quantum wells in the active region of the PN diode to form an electrically driven n-InP/InGaAs MQW/p-InP/p-InGaAs nanoscale LED.

A schematic diagram of the MQW LED component of the nanoscale column

Due to the growth pattern of the core shell, the nanometers grow from their nucleation position and extend beyond the oxide opening to reach the final diameter of about 1 mu m. Therefore, when the N doped core of the nanometers is directly contacted 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. 20/200nm's Ti/Au evaporates through an inclined electron beam to a highly P doped InGaAs contact layer, completing the component to form an electrical contact, in which a small portion of the nanoscale is exposed, and no metal is used as a window for the output of LED light.

The nano columnar LED was characterized by the quantum efficiency of 1510nm and about 30%. Although the space of the nanoscale LED is small, it can output 4 u W power, and the researchers claim that it is the highest optical output record that can be achieved from nanoscale / nanostructure LED. Under this setup, the available optical output is reduced to 200nW because of the collection efficiency of only 5%.

Another interesting aspect of the study is that the component can generate light gain by electric bias and show a strong light response in reverse injection, which helps to achieve photon integration on the chip.

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