Pulsed laser deposition of ITO/AZO transparent contact layers for GaN LED applications

Sin Liang Ou*, Dong Sing Wuu, Shu Ping Liu, Yu Chuan Fu, Shih Cheng Huang, Ray-Hua Horng

*Corresponding author for this work

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

In this study, indium-tin oxide (ITO)/Al-doped zinc oxide (AZO) composite films were fabricated by pulsed laser deposition and used as transparent contact layers (TCLs) in GaN-based blue light emitting diodes (LEDs). The ITO/AZO TCLs were composed of the thin ITO (50 nm) films and AZO films with various thicknesses from 200 to 1000 nm. Conventional LED with ITO (200 nm) TCL prepared by E-beam evaporation was fabricated and characterized for comparison. From the transmittance spectra, the ITO/AZO films exhibited high transparency above 90% at wavelength of 465 nm. The sheet resistance of ITO/AZO TCL decreased as the AZO thickness increased, which could be attributed to the increase in a carrier concentration, leading to a decrease in the forward bias of LED. The LEDs with ITO/AZO composite TCLs showed better light extraction as compared to LED with ITO TCL in compliance with simulation. When an injection current of 20 mA was applied, the output power for LEDs fabricated with ITO/AZO TCLs had 45%, 63%, and 71% enhancement as compared with those fabricated using ITO (200 nm) TCL for the AZO thicknesses of 200, 460, and 1000 nm, respectively.

Original languageEnglish
Pages (from-to)16244-16251
Number of pages8
JournalOptics Express
Volume19
Issue number17
DOIs
StatePublished - 15 Aug 2011

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