Recently, the Massachusetts Institute of Technology research team announced that the current design of a very practical silicon-based LED, it will use the forward bias method, compared with other silicon-based LED brightness increased by 10 times.
The new silicon-based LED developed this time adopts the forward bias method, and at the same time, the combination of the PN junction in the LED is changed, which successfully improves the photoelectric energy conversion efficiency of silicon materials, further improves the brightness of the silicon-based LED, and reduces the LED’s manufacturing cost.
For silicon materials, this is one of the most widely used materials by mankind, mainly used in the field of manufacturing semiconductor devices and integrated circuits. However, due to the particularity of silicon material, it has not been involved in the optical field, so silicon-based LED has not been realized.
The PN junction in the light-emitting diode includes a P area and an N area, which will determine the luminous efficiency of the diode. Among them, the N zone is full of exciting free electrons, and the P zone has positively charged holes that attract electrons in the P zone. As the electron rushes into the hole, the energy level of the electron drops sharply, and the energy difference can be released. However, different semiconductor materials have different electron and hole energies, so the energy released has certain differences.
Currently widely used materials such as gallium nitride and gallium arsenide are direct bandgap materials. They are often used in LEDs. The minimum conduction band and maximum valence band have the same electronic momentum. The electrons at the bottom of the conduction band and the top of the valence band The holes can emit light through radiation recombination, with a high recombination probability and high luminous efficiency.
As an indirect bandgap semiconductor material, silicon has different momentum values between the minimum conduction band and the maximum valence band. It tends to convert energy into heat rather than light, so its conversion speed and efficiency are not as good as others. material.
And this year, the research team led by Erik Bakkers of Eindhoven University of Technology in the Netherlands successfully developed a new type of silicon-germanium alloy luminescent material using VLS to grow nano-silicon wires, which successfully improved the above problems, and developed a new type that can be integrated through this material. To silicon-based lasers in existing chips. The successful development of this laser may significantly reduce the cost of data transmission and increase efficiency in the future.
This time, the MIT team further improved the use probability of silicon materials, and proposed a new connection method for N-zone and P-zone, changing the N-zone and P-zone from the traditional parallel arrangement to vertical stacking, so that the diode Keep electrons and holes away from the surface and edge areas to prevent electrons from converting electrical energy into heat, thereby improving luminous efficiency.
The American National Institute of Standards and Technology commented on this new silicon-based LED: “If you need low-efficiency, high-energy-consumption optical devices, then this new silicon-based LED is suitable for you. This LED is better than the current market. There are products, the manufacturing cost is much lower, not to mention the existing LED products have not been integrated on the chip.”
Rajev Ram, a researcher on the MIT research team, said that the characteristics of silicon-based LEDs are very consistent with the needs of short-range sensing, and revealed that the team will develop an all-silicon-based for short-range distance measurement for smartphone platforms. LED system.
It is reported that the new silicon-based LEDs introduced this time will be displayed at the IEEE International Electronic Devices Conference, and will have a wider range of application scenarios in short-range sensing. At the same time, the MIT research team is also preparing to integrate this new silicon-based LED into the CMOS chip and deliver it to GlobalFoundries for production in Singapore.