A Universal Method of Producing Transparent Electrodes Using Wide‐Bandgap Materials. (11th November 2013)

• Record Type: Journal Article
• Authors: Kim, Hee‐Dong; An, Ho‐Myoung; Kim, Kyoung Heon; Kim, Su Jin; Kim, Chi Sun; Cho, Jaehee; Schubert, E. Fred; Kim, Tae Geun
• Is Part Of: Advanced functional materials. Volume 24:Number 11(2014)
• Page Start: 1575
• Page End: 1581
• Publication Date: 2013-11-11
• Subjects: Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201301697
• Languages: English
• ISSNs: 1616-301X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A UV light‐emitting diode (LED) is an eco‐friendly optical source with diverse applications. However, currently, the external quantum efficiency (EQE) of AlGaN‐based UV LEDs, particularly in the UV‐C band (&lt;280 nm), is very low (&lt;11%) mainly due to a large optical absorption via <italic>p</italic>‐GaN contact layers. A direct Ohmic contact to <italic>p</italic>‐AlGaN layers should be obtained using UV‐transparent conductive electrodes (TCEs) to solve this problem. A universal method is presented here to make such contact using electrical breakdown, with wide‐bandgap materials, to form conductive filaments (CFs), providing a current path between the TCEs and the <italic>p</italic>‐(Al)GaN layers. The contact resistance between the TCEs and the <italic>p</italic>‐GaN layers (or <italic>p</italic>‐AlGaN) is found to be on the order of 10⁻⁵ Ω cm² (or 10⁻³ Ω cm²), while optical transmittance is maintained up to 95% for AlN‐based TCEs at 250 nm. These findings could be a critical turning point delivering a breakthrough in UV LED technologies.</p> </abstract>