title: Improved light extraction efficiency in GaN-based light emitting diode by nano-scale roughening of p-GaN surface.
abstract: Improvement in light extraction efficiency of Ultra Violet-Light Emitting Diode (UV-LED) is achieved by nano-scale roughening of p-type Gallium Nitride (p-GaN) surface. The process of surface roughening is carried out by using self assembled gold (Au) nano-clusters with support of nano-size silicon-oxide (SiO2) pillars on p-GaN surface as a dry etching mask and by p-GaN regrowth in the regions not covered by the mask after dry etching. Au nano-clusters are formed by rapid thermal annealing (RTA) process carried out at 600 degrees C for 1 min using 15 nm thick Au layer on top of SiO2. The p-GaN roughness is controlled by p-GaN regrowth time. Four different time values of 15 sec, 30 sec, 60 sec and 120 sec are considered for p-GaN regrowth. Among the four different p-GaN regrowth time values 30 sec regrown p-GaN sample has the optimum roughness to increase the electroluminescence (EL) intensity to a value approximately 60% higher than the EL intensity of a conventional LED.
authors.affiliation: Interdisciplinary Program of Photonics Engineering, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Sang Jae
authors.initials: SJ
authors.lastname: Park
authors.forename: Karthikeyan Giri
authors.initials: KG
authors.lastname: Sadasivam
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Chung
authors.forename: Gi Cheol
authors.initials: GC
authors.lastname: Hong
authors.forename: Jin Bong
authors.initials: JB
authors.lastname: Kim
authors.forename: Sang Mook
authors.initials: SM
authors.lastname: Kim
authors.forename: Si-Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Seong-Ran
authors.initials: SR
authors.lastname: Jeon
authors.forename: June Key
authors.initials: JK
authors.lastname: Lee