Verticle Announces High Current Copper-Based UV LED Chips

Silicon Valley LED chip company Verticle (made in Korea) has recently developed a hexagonal copper-based UV LED that is resistant to high currents. The chip uses a chemical chip separation technique between copper-based and gallium nitride-based UV LEDs. Although UV LEDs have many advantages, due to their low internal quantum efficiency, UV LED optical power is not as good as blue LEDs.

Increasing the quantum efficiency of the UV epitaxial wafer is not achievable in a short period of time. However, by increasing the input current of the UV LED and controlling the heat generation, the total power can also be increased. Verticle said that the thermal drooping problem of UV LEDs is more prominent than Blu-ray LEDs, so lowering the junction temperature is the main challenge facing the company.

In order to increase the injection current and heat dissipation level, the Verticle UV LED chip uses a copper substrate. The copper-based vertical chip has a thermal resistance (Rth) of 2K/W, which is lower than that of a gallium nitride/silicon vertical chip. Therefore, the gallium nitride/copper junction temperature (Tj) is lower than that of gallium nitride/silicon. When the injection current is 350 mA, the junction temperature difference between the two chips is 2 degrees Celsius. However, when the injection current is 1 A, the junction temperature difference is larger.

The company pointed out through testing that the vertical copper-based UV LED chip has higher radiant flux than the horizontal copper-based UV LED chip with the same epitaxial wafer. Moreover, the copper-based ultraviolet LED chip has a higher withstand current than other vertical chips.

For example, when the injection current is 1A, the gallium nitride/copper ultraviolet LED chip is not saturated, and the gallium nitride/sapphire chip begins to saturate after the injection current exceeds 500 mA. This shows that the GaN/Chip chip has a higher heat dissipation capability than other material-based GaN GaN chips, providing unique technical advantages for applications requiring high injection current and good heat dissipation.

Verticle's hexagonal UV LED chip (size 45 mil) has a radiant flux measurement at 392 nm wavelength: 416 mW for 350 mA injection current, 787 mW for 700 mA injection current, and 1025 mW for 1 A injection current.