LED Chip Technology and Difference Analysis at Home and Abroad
Time: 2019-05-17 Reads: 6 Edit: Admin
LED Chip Technology and Difference Analysis at Home and Abroad

Chip is the core component of LED. At present, there are many manufacturers of LED chips at home and abroad, but there is no uniform standard for chip classification. If it is classified by power, it can be divided into high-power and low-power. If it is classified by color, it can be divided into red, green and blue. If it is classified by shape, it can be divided into square and round chips. If it is classified by voltage, it can be divided into low-voltage DC chips and high-voltage DC chips. In terms of comparison of chip technology at home and abroad, foreign chip technology is new, while domestic chip technology is not heavy.

 

Substrate Material and Wafer Growth Technology

 

At present, the key to the development of LED chip technology lies in the substrate material and wafer growth technology. In addition to the traditional sapphire, silicon (Si), silicon carbide (SiC) substrate materials, zinc oxide (ZnO) and gallium nitride (GaN) are also the focus of current LED chip research. At present, sapphire or silicon carbide substrates are mostly used for epitaxy growth of broad-band gap semiconductor GaN. These two materials are very expensive and monopolized by large foreign enterprises. The price of silicon substrates is much cheaper than sapphire and silicon carbide substrates, which can produce larger size substrates, improve the utilization of MOCVD, and thus improve the core yield. Therefore, in order to break through international patent barriers, Chinese research institutes and LED enterprises begin to study silicon substrate materials.

                                                 

But the problem is that the high quality combination of silicon and GaN is the technical difficulty of LED chips. The high defect density and cracks caused by the huge mismatch of lattice constants and thermal expansion coefficients of silicon and GaN hinder the development of chip field for a long time.

 

Undoubtedly, from the perspective of substrate, the mainstream substrates are sapphire and silicon carbide, but silicon has become the future trend in the chip field. For China, where the price war is relatively serious, silicon substrates have more cost and price advantages: silicon substrates are conductive substrates, which can not only reduce the core area, but also eliminate the steps of dry etching of GaN epitaxial layer. In addition, the hardness of silicon is lower than sapphire and silicon carbide, and some cost savings can be achieved in processing.

 

At present, most of the LED industry is based on 2-inch or 4-inch sapphire substrates. If the silicon-based GaN technology can be used, at least 75% of the raw material cost can be saved. According to the estimates of Sanken Electric Company of Japan, the cost of making large-scale blue-light GaN LED on silicon substrates will be 90% lower than that on sapphire substrates and silicon carbide substrates.

 

There are great differences in chip technology at home and abroad

 

Overseas, first-class enterprises such as Osram, Prey, Japan Sanken have made breakthroughs in the research of GaN-based LEDs on large-scale silicon substrates. International LED giants such as Philips, Samsung, LG, Toshiba and so on have also set off a research upsurge of GaN-based LEDs on silicon substrates. Among them, in 2011, Prey developed a high light efficiency GaN-based LED on 8-inch silicon substrates, and achieved a luminous efficiency of 160 lm/W comparable to the top level LED devices on sapphire and silicon carbide substrates. In 2012, Osram successfully produced 6-inch silicon-based GaN-based LED.

 

In contrast, in mainland China, the breakthroughs of LED chip enterprises are mainly to increase production capacity and large-scale sapphire crystal growth technology. In addition to the successful production of GaN-based high-power LED chips on 2-inch silicon substrate by crystal energy photovoltaics in 2011, there is no major breakthroughs in the research of GaN-based LED on silicon substrate by Chinese chip enterprises. At present, the mainland Chinese LED chip enterprises are still mainly engaged in production capacity. Sapphire substrate materials and wafer growth technology, Sanan Optoelectronics, , Tongfang shares and other mainland chip giants have also made breakthroughs in production capacity.