Graphical technology for sapphire substrates

At present, most of the LED industry uses sapphire as the substrate material for epitaxial growth. With the increasing demand for LED brightness in the industry, various methods for improving light extraction have been implemented, and a patterned substrate is one of them.

PSS technology is a derivative of the lateral extension (ELOG) technology. ELOG technology is a technique to reduce dislocation density by increasing the lateral growth rate so that dislocation bending does not extend to the growth surface. Since the ELOG technology requires SiO2 or SiNx as a mask, the growth process needs to be interrupted and the growth period is long, and the growth mask also causes contamination of the growth surface and the like. In 2000, Ashby et al. adopted a method of single-step GaN growth on a sapphire substrate with a strip structure. They found the hangar extension of GaN in the trench region of the substrate, which is the prototype of PSS technology. In 2001, Tadatomo et al. proposed the use of dry etching to prepare PSS with periodic fringes, which effectively improved the external quantum efficiency.

The graphics preparation process of PSS is as follows:

At present, many companies in China are using PSS technology, such as Sanan, Dehao, Hualei, Huacan and so on. The PSS graphics are different for each family, and each company adjusts the graphics structure through its own process control. However, the general types of graphic structures are as follows:

One of the future development technologies: multiple PSS

The above picture is also the development process of PSS, and it is different to look at such a variety of graphics. The development of PSS technology will grow in the efforts of various companies. Professor Zhang Guoyi from Peking University summarized the development trend of PSS technology as:

The graphics substrate has grown from 2 inches to 4 inches and is growing in size.

Graphic structure is optimized from simple to complex

Graphics size is developed from micron to nanoscale, etc.

PSS technology is one of the many technologies in our LED industry. At present, many sapphire substrate companies directly provide substrates with PSS, and can future graphics be standardized? The upstream enterprises help downstream to complete some processes, which is the phenomenon of industrial integration. what.