Recently, with the rapid development of high pixel-density LED display screen, the small pixel-pitch display which usually knows for its pixel-pitch smaller than 2.5, including 2.5,2.0,1.8,1.5 was applied more and more.

Compared with DIP, LCD and more display, high-density LED display features with some obvious advantages as below, HD, high fresh rate, seamless stitching, good heat dissipation and easy installation. At the same time, these advantages accompany with challenge for technology, especially when pixel-pitch smaller than 1mm.

High-density LED display application required high scan rate, high refresh rate and high gray scale. The decrease of pixel pitch from 3 to 2 then to 1 even to 0.X which means the amount of LED chips increase at the same time puts forward higher request for LED chips.

To reduce the LED chip driving cost, high-density LED display adopted dynamic scan method. As the increasing of LED density, the scan ratio will also increase in order to reduce the driving cost and control the circuit configuration pressure. Only LED chips with high back pressure can meet the need of high scan ratio.

The control of LED display gray-scale, to avoid flash, LED display should equip with high refresh ratio which demands short switch time and LED chips can response at such short time. Short LED response time means high request for LED epitaxial materials and LED structure design. Therefore, Scientific optimization of epitaxial materials and keep the good stability of MOCVD system and program are necessary.