High Brightness GaN LEDs with Engineered Sapphire Substrate

The GaN based epitaxial systems are emerging as a front- runner for a variety of opto-electronic applications, such as LEDs and HEMTs. One major application is for solid state lightning, and essential requirements are high brightness, stable color rendering index and efficient heat dissipation. The significant problem is the sapphire substrate on which GaN is grown. Sapphire substrate is not recommended from the device point of view, and hence has to be removed or engineered for better device performance. In this work we have developed via-holes in sapphire filled with nanofiller material and studied the device behavior with the aim of having better heat dissipation. The devices made up of green and blue LEDs exhibited superior performance in terms of sharp turn-on voltage, output power and temperature stability.