Silicon substrate light-emitting diode LED lighting development speed

The American progressive female journalist Anna Louis Strong has such a famous saying: "It is better to ignite a bright candle than to curse the darkness." The journey of mankind starts from the darkness, but always moves toward the light. In ancient times, the torches used by the beasts were expelled. The incandescent lamps that have illuminated thousands of households since the scientific revolution are the best proof of people's pursuit of light.

With the further understanding of the earth's resources, human beings are not satisfied with the existing lighting methods. On the contrary, they are still looking for a more energy-efficient and environmentally-friendly source of light. In this context, LEDs are born out of the world. . Among them, the "Si-substrate high-efficiency GaN-based blue light-emitting diode" technology, which won the first prize of China's national technology invention, is the lighting industry "Shujin Live Bone", which is expected to accelerate the commercialization of LEDs.

Three LED lighting technology routes

A light-emitting diode (LED) is a solid-state semiconductor device that directly converts electrical energy into visible light. Its core structure is a semiconductor wafer, one end of which has a negative pole at one end and is entirely encapsulated by epoxy resin. The principle of power generation is that the P-type semiconductor and the N-type semiconductor inside the wafer form a PN junction. When a current passes through the wire, electrons are pushed from the N region to the P region, and energy is emitted in the form of photons to generate bright light.

At present, the LED lighting industry is a strategic emerging industry that is mainly developed at home and abroad. In general, there are three technical routes: sapphire substrate, silicon carbide substrate and silicon substrate. The sapphire substrate was proposed by Japanese scientists and the three inventors also won the 2014 Nobel Prize in Physics. Its advantages are mature production technology and good device quality; sapphire itself has good stability and can adapt to high temperature process; in addition, sapphire has high mechanical strength and is easy to handle and clean, so sapphire substrate has become the mainstream choice.

The second technological road is the silicon carbide substrate, also known as the “noble route”, which is expensive and the main contributor receives the US President’s Technology Invention Award. Silicon carbide is the third generation of new semiconductor materials following the first generation of silicon, germanium and second-generation gallium arsenide. As a substrate material, its application is second only to sapphire, with good chemical stability, good electrical conductivity, good thermal conductivity, and no absorption of visible light. Such a substrate can better solve the heat dissipation problem and has an important position in the field of semiconductor lighting technology.

The silicon substrate route is proposed by researchers from Nanchang University and Jingneng Radio and Television Co., Ltd. in China. Compared with sapphire and silicon carbide, silicon has the advantages of low cost, large size, high quality and conductivity, and is considered to be the most promising. Blue LED substrate material. The chip electrode of the silicon substrate can adopt two kinds of contact modes, namely horizontal contact and vertical contact, and can be called L-shaped electrode and V-shaped electrode. The two electrodes determine the current inside the silicon substrate LED chip, and the current can flow either laterally or longitudinally. The longitudinal flow can increase the light-emitting area of ​​the LED and improve the light-emitting efficiency of the diode. In addition, silicon is a good thermal conductivity body. The thermal conductivity of the device is enhanced by the silicon substrate, and the service life of the diode is significantly prolonged. It can be said that the high-efficiency and environmental protection "two mistakes", the market prospects "have a look."

Semiconductor lighting will help promote the new high-speed data transmission technology of "optical communication"

Is the development of silicon-based LED lamps only solving the lighting problem? No, semiconductors are a kind of material between the insulator and the conductor, and the "double-role conversion" can be completed as long as the conditions are suitable. The huge potential of the application determines that the research progress of LEDs is bound to have a collateral effect, and the most conspicuous one is the "optical communication" technology.

When it comes to "optical communication," the most easily remembered allusion is "the bonfire drama princes", but don't think that it is fiber-optic communication. It is called "visible light communication technology" and refers to the use of visible light bands as information carriers. After "meeting" with LED lights, "optical communication" technology is expected to become a new high-speed data transmission technology that uses the light of semiconductor lighting to achieve "lighting to the Internet."

It is reported that there are about 44 billion lamps in the world, which constitutes a huge lighting network. The silicon substrate LED lamp has significant energy saving and emission reduction value, and can replace the traditional light source to save electricity by 40% to 80%. As long as a microchip is added to the LED, the energy-saving light source "seconds" wireless network transmitter, tens of billions of LED lighting equipment will build a huge visible light communication network.

It is conceivable that in the future, every lamp can become a high-speed network hotspot. Cars, buses, high-speed rails and even airplanes can be connected to the Internet at high speed by means of LED light sources. Some of the hot topics, such as indoor networks, Internet of Things, Internet of Vehicles, Industry 4.0, smart cities, including defense communications, can be “affordable” in “optical communication” networks. The silicon substrate LED lamp provides an inexpensive access method for the realization of "Internet +", and because of its energy saving and environmental protection, it brings a "green red envelope" before the new round of hardware update trend!

The silicon substrate technology route is the only opportunity that may break through the foreign patent blockade.

The mainstream technology route has already been established, and the characteristic technology route has also been formed. Is the "face value" of the silicon substrate LED lamp only the eye-catching "saving money"? Nor is it. China is a veritable LED manufacturing country, and the research and development of this technology has made the international market a stable situation of “three pillars”.

In the past, due to the long-term monopoly of the former two lighting technologies by the US and Japanese companies, domestic LED companies were limited to price barriers and used sapphire technology routes, which were filled with patent mines carefully buried by LED giants. In the 1990s, the scenes of the fierce killing of DVD patents by American and Japanese companies were vividly witnessed. In the past 10 years, many domestic LED companies have repeated the same mistakes and swallowed bitter results. The silicon substrate research team believes that the efforts of foreign LED manufacturers to "release water and raise fish" are pure and green, and patent wars may be triggered at any time. The technical route of the silicon substrate that appeared at this time is undoubtedly "timely rain" and becomes "the only chance that it is possible to break through the foreign patent blockade."

Throughout the history of LED development, US companies first developed visible light LEDs, while Japanese companies acquired blue LEDs with Nakamura Shuji's GaN research. Nowadays, China's school-enterprise cooperates in research and development of silicon substrate technology. On the road of LED development, there is a third national flag. It has to be said that "technology has no borders"!

Looking forward to the next decade, energy-saving LED lamps on silicon substrates are likely to replace ordinary sunshine lamps and traditional LED lamps and enter thousands of households. As mentioned above, the visible light communication technology equipped with LED lights will effectively break through the radio spectrum carrying capacity and create the next generation radio communication technology.