Advanced Technologies for high efficiency GaInN LEDs for solid state lighting

摘要

Solid state lighting has seen a rapid development over the last decade. They compete and even outperform ligth sources like incandescent bulbs and halogen lamps. LEDs are used in applications where brightness, power consumption, reliability and costs are key parameters as automotive, mobile and display applications, In the future LEDs will also enter the market of general lighting. For all of these new applications highly efficient, scalable and cost efficient technologies are required. These targets can be matched by SiC based flip chip LEDs which enable the design of high current chips with efficiencies of up to 28 lm/W in white solderable packages. An alternative approach is the implementation of thinfilm technology for GalnN. The LED is fabricated by transferring the epilayers with laser lift off from sapphire to a GaAs host substrate. In combination with efficient surface roughening and highly reflective p-mirror metallisation an extraction efficiency of 70% and wall plug efficiency of 24% at 460nm have been shown. The chips showed 16mW@ 20mA with an Voltage of 3.2V. The technology is scalable from small size LEDs to high current Chips and is being transferred to mass production.