Characteristic enhancement of the blue LED chip by the growth and fabrication on patterned sapphire (0 0 0 1) substrate

Blue light-emitting diodes (LEDs) with an InGaN multi-quantum well (MQW) structure were fabricated on a patterned sapphire substrate (PSS) using a single growth process of metal organic chemical vapor deposition (MOCVD). The electrical and optical properties of these LEDs were investigated. The crystal quality of epitaxial GaN film was improved by using the PSS structure. At 40 mA injection current, the peak wavelength and the full-width at half-maximum of the electroluminescence spectra of PSS were 461 and 24 nm, respectively. The electroluminescence intensity (EL) of LEDs grown on patterned substrate was 2.44 times greater than that of unpatterened sapphire substrate (UPSS). The operating voltage was measured about 3.1 V for the LED with a PSS structure. This significant increase resulted from the improvement of the epitaxial quality of the InGaN/GaN epilayers and the improvement of the light extraction efficiency through patterned sapphire substrates.