advisor : p. c. yu speaker : g. s. hong

Nanostructured broadband antireflection coatings on AlInP fabricated by nanoimprint lithography

Advisor : P. C. YuSpeaker : G. S. Hong

Optoelectronics Research Centre, Tampere University of Technology, Korkeakoulunkatu 3, 33720, Tampere, P.O. Box 692, 33101 Tampere, Finland

Outline

Introduction Experiment Results Conclusion

Moth-eye AR structures.

AlInP has a very large band gap (1.3~2.4eV) and high transparency.

This letter demonstrates moth-eye antireflection coatings fabricated by UV-nanoimprint lithography (NIL) on AlInP/GaAs structure.

Introduction

moth’s head moth-eye

Fabrication

The yield is approximately 95% over an 4 cm^2 consisted of 4.4x1e9 nanocones.

Arrays of metallic nanocones fabricated by UV-nanoimprint lithographyJuha M. Kontio *, Janne Simonen, Juha Tommila, Markus PessaOptoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FIN-33101, Tampere, Finland

Fabrication steps (1)

Laser interference lithography (LIL) UV - NIL

http://0rz.tw/mev4Chttp://0rz.tw/IAGJV

Fabrication steps (2)

PMMA Si

GeUV-NIL resist

Structure in Simulation

A :30/170/370 nm (top diameter/base diameter/height) B : 50/220/370 nmC : 80/300/440 nmReference : 1 um AlInP

Simulation & Measurement

The simulated values are lower than the measured ones partly due to :

The imperfect model of the dielectric function.

The roughness of the etched surfaces.

The silver mirror used as a reference in the measurements.

Arithmetic average reflectivities

Reflection of the laser GaAs’PLAbsorption of the laser and the PL in the AlInP layer

PL intensities

Conclusion

An average reflectivity of 2.7% was achieved for wide spectral range 450–1650 nm.

Using PL measurements, we have shown that the surface recombination and patterning induced losses are low.

Thanks for your attention !