High-power deep ultraviolet light-emitting diodes basedon a micro-pixel design

Using a micro-pixel design, we report the demonstration of high-power deep UV AlGaN-based light-emitting diodes (LEDs) with peak emission wavelength at $280nm$⁠. The design comes in response to lateral current crowding problems, which severely limit the maximum possible active area and the overall performance of ordinary square geometry III-nitride LEDs fabricated on insulating substrates. It is shown that the interconnected micro-pixel geometry significantly reduces both the device series resistance and the thermal impedance, thereby improving heat dissipation and increasing the maximum optical power. The design imparts ever-increasing advantages as the operating wavelength decreases (and the aluminum content increases). The optical power of the $10×10pixel$ array with an effective area of $222×222μm2$ only saturates at dc currents higher than $200mA$⁠, which is nearly 50% greater than found for a square geometry LED with identical junction area, fabricated from the same wafer. These $280nm$ LEDs demonstrated a high on-wafer cw power of $145μW$ with $200mA$ of pumping current.