Hexagonal arrays of submicron polymer patterns with a high refractive index were fabricated on a vertical light-emitting diode (LED) device by means of nanoimprint lithography (NIL) to improve the light extraction efficiency. An organic-inorganic hybrid resin containing a polymeric titanium dioxide precursor was spin-coated on the n-GaN top layer of a vertical LED wafer. The coated layer was then imprinted for 10 min with an elastomeric polydimethylsiloxane stamp at 200 °C and 5 atm. The NIL process formed pillar patterns on the n-GaN layer of the vertical LED wafer. The pillar patterns have a high refractive index (n ≈ 2.0) in the visible wavelength range; they also have a diameter of 200 nm and a pitch of 700 nm. The light output power of the patterned vertical LED device is 28% greater than that of a non-patterned vertical LED device with a driving current of 350 mA. The I-V characteristics of the vertical LED device confirm that the patterning process induces no electric degradation.
Bibliographical noteFunding Information:
This work is the outcome of a Manpower Development Program for Energy & Resources supported by the Ministry of Knowledge and Economy (MKE). It was partly supported by the IT R&D program of MKE/IITA ( 2009-F-025-01 , Development of Core Technology for High Efficiency Light Emitting Diode based on New Concepts) by the MKE (The Ministry of Knowledge Economy), Korea, under the “In-depth support to tackle bottleneck technologies for small and medium sized business” support program.
- Light extraction efficiency
- Polymer pattern with a high refractive index
- Vertical light-emitting diodes
ASJC Scopus subject areas
- General Materials Science
- General Physics and Astronomy