Performance-improved vertical GaN-based light-emitting diodes on Si substrates through designing the epitaxial structure

Abstract

Performance-improved vertical GaN-based light-emitting diodes (LEDs) have been fabricated on Si substrates through designing the epitaxial structures with a combination of an AlN interlayer and a SiN_x interlayer. The AlN interlayer is used to introduce more compressive stress in GaN epitaxial films to balance the tensile stress formed in thick n-GaN epitaxial films from cracking, and the SiN_x interlayer is employed to annihilate the dislocation density to improve the crystalline quality of GaN epitaxial films. By using the optimized epitaxial structures, high-quality crack-free GaN-based LED wafers have been obtained. The full-widths at half-maximum from the GaN(0002) and GaN(10−12) X-ray rocking curves are as small as 280 arcsec and 310 arcsec, respectively. The hetero-interfaces of the InGaN/GaN multiple quantum wells are sharp and abrupt. After the LED wafers are fabricated into vertical LED chips, they reveal high-performance with a high light output power of 595 mW and a small working voltage of 2.75 V with an electroluminescence dominant wavelength of 456 nm @ 350 mA, corresponding to a wall-plug efficiency (WPE) as high as 61.8%. These performance-improved vertical LED chips open a broad prospect in the application of high-end lighting applications.