title: InGaN light-emitting diodes with oblique sidewall facets formed by selective growth on SiO₂ patterned GaN film.
abstract: In this study, GaN-based light-emitting diodes (LEDs) with naturally formed oblique sidewall facets (OSFs) were fabricated through a selective regrowth process. The SiO₂ mask layer was patterned on a heavily doped n-GaN template layer rather than on a sapphire substrate. As a result, the periphery of the LED included several OSFs around the regrown GaN mesa. While processing the device, dry etching was unnecessary for exposing the n-GaN underlying layer in order to form the n-type Ohmic contacts. This could be attributed to the fact that the n-GaN template layer with an electron concentration of around 8 × 10¹⁸/cm³ was exposed after the removal of the SiO₂ mask layer. With an injection current of 20 mA, GaN-based LEDs with OSFs exhibited a 21% enhancement in light output compared with those that have vertical sidewall facets. The enhancement is attributed to the fact that photons extracted from OSFs can reduce internal absorption loss.
authors.affiliation: Institute of Electro-Optical Science and Engineering, Advanced Optoelectronic Technology Center & Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan City 70101, Taiwan. jksheu@mail.ncku.edu.tw
authors.forename: Jinn-Kong
authors.initials: JK
authors.lastname: Sheu
authors.forename: Kuo-Hua
authors.initials: KH
authors.lastname: Chang
authors.forename: Shang-Ju
authors.initials: SJ
authors.lastname: Tu
authors.forename: Ming-Lun
authors.initials: ML
authors.lastname: Lee
authors.forename: Chih-Ciao
authors.initials: CC
authors.lastname: Yang
authors.forename: Che-Kang
authors.initials: CK
authors.lastname: Hsu
authors.forename: Wei-Chih
authors.initials: WC
authors.lastname: Lai