InGaN/GaN Blue Light Emitting Diodes Using Freestanding GaN Extracted from a Si Substrate

Abstract

We demonstrate the first InGaN/GaN blue light emitting diodes (LEDs) on freestanding GaN grown using a Si substrate. Transmission electron microscopy and X-ray diffraction analysis revealed that the InGaN/GaN multi quantum wells (MQWs) on freestanding GaN grown using Si substrates have excellent structural properties suitable for high-performance optical devices. Photoluminescence measurements confirm the high crystal quality of the InGaN/GaN MQWs and remarkable emission wavelength uniformity with a standard deviation of 0.68%. Light–current–voltage characteristics indicate that the InGaN/GaN LEDs on freestanding GaN grown using a Si substrate exhibit a forward voltage of 3.75 V at a current of 20 mA and rectifying characteristics with very low leakage current and high breakdown voltage. Furthermore, they provide stable blue electroluminescence (λ = 460 nm) with a small variation in the emission wavelength of 0.2% over a 2 in. area. The internal quantum efficiency of InGaN/GaN LEDs on freestanding GaN grown using Si substrates is remarkable at ∼80%. Despite using Si substrates as the support, the optoelectronic properties of the InGaN/GaN LEDs are outstanding. We believe that the InGaN/GaN LEDs based on freestanding GaN crystals extracted from Si substrates are promising for the development of GaN-based high-performance devices.