| Deep UV emitters have been made possible using Gallium Nitride (GaN) with its compound alloys mainly ternary compound Aluminum Gallium Nitride (AIGaN) and quaternary compound Aluminum Indium Gallium Nitride (AlInGaN) both on Sapphire and Silicon Carbide (SiC) substrates. Among these substrates, sapphire offers a natural choice for better light extraction for short wavelength emitters. Optical power of sapphire based UV LED is two orders of magnitude higher than that on SiC, but has lower external quantum efficiencies and show pre-mature saturation in optical power as compared to the contemporary III-Nitride visible emitters. This effect is attributed to severe self-heating in these LEDs that increases the device temperature even at low operating currents. The thermally insulating nature of sapphire substrate further impedes the heat dissipation from these LEDs thus aggravating the thermal effects. Hence, a novel approach of flip-chip packaging technique is employed to realize low thermal resistance packaging for effective thermal management of these LEDS. Improvement in both thermal management and light extraction is achieved by flip-chip packaging and customized header designs. This report gives an insight into achieving the desired task, i.e. “High efficiency deep UV Solid-State Emitters”. |
