Vertically Mounted InGaN-on-Sapphire Light-Emitting Diodes
– L Zhu, ZT Ma, PT Lai, and HW Choii
IEEE Transactions on Electron Devices, vol. 58, 2, pp. 490-494 (2011)
An InGaN/GaN light-emitting diode (LED) chip mounted in a vertical configuration (vmLED) is demonstrated, exhibiting significant enhancement to light extraction, compared with a LED mounted in a conventional planar geometry. By flipping the chip orthogonally, two large illumination surfaces of the device are exposed for direct light extraction. Comparisons, through ray-trace modeling and experiment data with conventional surface-mounted LEDs, indicate that the vmLEDs achieve superior light extraction efficiency. A sapphire-prism-mounted vmLED is further proposed to improve heat sinking, which is well suited for higher current operations.
