Advisor : P. C. Yu Speaker : G. S. Hong

1. Nanostructured broadband antireflection coatings on AlInP fabricated by nanoimprint lithography Advisor : P. C. Yu Speaker : G. S. Hong Optoelectronics Research Centre, Tampere University of Technology, Korkeakoulunkatu 3, 33720, Tampere, P.O. Box 692, 33101 Tampere, Finland

2. Outline • Introduction • Experiment • Results • Conclusion

3. Introduction • 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-nanoimprintlithography (NIL) on AlInP/GaAsstructure. moth’s head moth-eye

4. Fabrication The yield is approximately 95% over an 4 cm^2 consisted of 4.4x1e9 nanocones. Arrays of metallic nanocones fabricated by UV-nanoimprintlithography Juha M. Kontio *, Janne Simonen, Juha Tommila, Markus Pessa Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FIN-33101, Tampere, Finland

5. Fabrication steps (1) Laser interference lithography (LIL) UV - NIL http://0rz.tw/IAGJV http://0rz.tw/mev4C

6. Fabrication steps (2) UV-NIL resist Ge PMMA Si

7. Structure in Simulation

8. Simulation & Measurement A :30/170/370 nm (top diameter/base diameter/height) B : 50/220/370 nm C : 80/300/440 nm Reference : 1 um AlInP

9. Arithmetic average reflectivities • 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.

10. PL intensities Absorption of the laser and the PL in the AlInP layer GaAs’PL Reflection of the laser

11. 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.

12. Thanks for your attention !