Microfabrication of Organic Crystal Photosensors
authors Serra, João M. P. S.; Sequeira, Sara I. H.; Domingos, Ismael D.; Oliveira, Ana P. P.; Cardoso, Susana; Alves, Helena C. R. J. D. e Leitão, Diana C. P.
nationality International
abstract ORGANIC SINGLE-CRYSTALS ARE WELL SUITED AS PHOTOSENSITIVE DEVICES DUE TO PROPERTIES SUCH AS HIGH CHARGE MOBILITY [1, 2] AND QUANTUM EFFICIENCY [3]. MINIATURIZING THESE DEVICES IS A NOTABLE ENGINEERING CHALLENGE, AS THE ABSORPTION OF LIGHT DECREASES AS WE REDUCE THE DIMENSIONS OF THE DEVICE [4]. WE CAN OVERCOME THIS LIMITATION BY COUPLING LIGHT INTO A GUIDED MODE, SUCH AS WHISPERING GALLERY MODES (WGMS) [5], IN WHICH LIGHT IS FORCED TO RECIRCULATE INSIDE A CIRCULAR RESONATOR, INCREASING THE OPTICAL PATH. THIS WORK TARGETS THE MICROFABRICATION AND CHARACTERIZATION OF PHOTOSENSORS USING RUBRENE CRYSTALS PATTERNED INTO CYLINDRICAL SHAPES (WITH 20 ΜM AND 50 ΜM DIAMETERS) TO PROMOTE COUPLING TO WGMS. THIS PATTERNING PROCESS IS ACHIEVED USING CONVENTIONAL MICROFABRICATION TECHNIQUES AND REQUIRES A THOROUGH OPTIMIZATION OF REACTIVE ION ETCHING END POINT CONTROL. THE PHOTORESPONSE OF THE FABRICATED DEVICES IS THEN CHARACTERIZED AND COMPARED BETWEEN DIFFERENT GEOMETRIES, WITH THE FLUORESCENCE SPECTRUM OF THE DEVICES ANALYZED USING CONFOCAL MICROSCOPY. REFERENCES [1] Hong-Hua Fang, Ran Ding, Shi-Yang Lu, Yue-De Yang, Qi-Dai Chen, Jing Feng, Yong-Zhen Huang, Hong-Bo Sun, “Whispering-gallery mode lasing from patterned molecular single-crystalline microcavity array,” Laser & Photonics Reviews, 7(2):281–288, 2013. [2] Shi-Yang Lu, Hong-Hua Fang, Jing Feng, Hong Xia, Tie-Qiang Zhang, Qi-Dai Chen, Hong-Bo Sun Lu, “Highly stable on-chip embedded organic whispering gallery mode lasers,” Journal of Lightwave Technology, 32(13):2415–2419, 2014. [3] Rui M. Pinto, Ermelinda S. Maçôas, Helena Alves, “Photoconductive response in organic charge transfer interfaces with high quantum efficiency,” Nature Communications,4:1842, 2013. [4] Jonathan Grandidier, Dennis M. Callahan, Jeremy N. Munday, Harry A. Atwater, “Light Absorption Enhancement in Thin-Film Solar Cells Using Whispering Gallery Modes in Dielectric Nanospheres,” Advanced Materials, 23(10):1272–1276, 2011. [5] Vladimir S Ilchenko, Andrey B Matsko, “Optical resonators with whispering-gallery modes - Part I: Basics,” IEEE Journal of selected topics in quantum electronics, 12(1):3-14, 2006.
year published 2018