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.
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.