High output power InGaN ultraviolet light-emitting diodes fabricated on patterned substrates using metalorganic vapor phase epitaxy

Ultraviolet (UV) light-emitting diodes (LEDs) with an InGaN multi-quantum-w ell (MQW) structure were fabricated on a patterned sapphire substrate (PSS) using a single growth process of metalorganic vapor phase epitaxy. In this study, the PSS with parallel grooves along the [11 (2) over bar0](sapphire ) direction was fabricated by standard photolithography and subsequent reac tive ion etching (RIE). The GaN layer grown by lateral epitaxy on a pattern ed substrate (LEPS) has a dislocation density of 1.5 x 10(8) cm(-2). The LE PS-UV-LED chips were mounted on the Si bases in a flip-chip bonding arrange ment. When the LEPS-UV-LED was operated at a forward-bias current of 20 mA at room temperature, the emission wavelength, the output power and the exte rnal quantum efficiency were estimated to be 382 nm, 15.6 mW and 24%, respe ctively. With increasing forward-bias current, the output power increased l inearly and was estimated to be approximately 38 mW at 50 mA.