poster reu 2016
TRANSCRIPT
3-hydroxyphenalenone (3-HPLN) was chosen as the source material to prepare organic thin films on Al2O3 substrates
Films were deposited using thermal evaporation under high vacuum. (EvoVac)
Substrate temperature was adjusted to control the film morphology
Atomic Force Microscopy (AFM) was used to measure the surface morphology of the thin films
This work was supported by the National Science Foundation (NSF) through the Centers of Research Excellence in Science and Technology (CREST, HRD-1345163), and by the Nebraska Materials Research Science and Engineering Center (MRSEC, DMR-1420645).
Dr. Yuewei Yin, Kishan Kumar Sinha, Xiaozhe Zhang; Physics and Astronomy, UNL
Thank you to UNL Physics and Astronomy Department, for hosting this internship.
Organic electronics are gaining relevance due to their flexibility and low cost. In particular, organic thin films play critical roles in these applications for replacing certain inorganic counter parts.
Preparing organic thin films of smooth morphology is necessary for application. Here we study the effect of growth conditions on film morphology in physical vapor deposition processes.
Abstract
Purpose
Comparison of 3-HPLN and Croconic Acid
Analysis
Conclusion
Acknowledgements
Procedure Clean the Al2O3 substrate which is then placed inside the
chamber. Pump down the chamber to high vacuum (110 -7 Torr) Begin to heat the organic source to the sublimation point;
cooling down the substrate if needed. Open the shutter to allow the organic molecules to deposit onto
the substrate. AFM for morphology characterization.
Instrumentation
References1 Slashgear.comhttp://www.slashgear.com/lg-pumps-8-7bn-into-oled-for-your-car-tv-and-wrist-27416167/
Line scan of the images at RT (left) and -80 °C (right).
EvoVac Deposition:High vacuum for
sublimation of organic materials.
Variable substrate temperature from -160C to 200C for controlling the film growth
3-HPLN at -15C:• Thickness: 40nm
• Abled to see some holes on the surface.
3-HPLN at RT:• Thickness: 40nm
• Grown close together, not smooth
3-HPLN at -80C• Thickness: 40nm
• Grew in Island style wouldn’t be a good surface
A Study of the Morphology of Organic Thin Films:
Nicole Lopez1, Xuanuan Jiang2, Dr. Xiaoshan Xu2
1Department of Physics, California State University, San Bernardino, CA, USA2Department of Physics and Astronomy at University of Nebraska-Lincoln, NE, USA
Surface Morphologies
Croconic Acid(CA) at -30C: Covered the whole
substrate surface Has low roughness
of 3.5nm.
3-HPLN at -30C:• Thickness: 40nm
• Rough but has a nearly continues surface.
Atomic Force Microscope(AFM):Scanning probe to
determine the surface morphology
Surface roughness, coverage can be found from the AFM images
Vaporized material
Deposition of thin film
Source Material Heater
Vacuum Chamber
Source Holder3-HPLN at -30C: Covered most of
the surface, can observe some holes.
Has high roughness of 50nm .
Nebraska
MRSEC
The picture to the left shows how the flexibility of the organic thick films may impact and even revolutionize the consumer electronics1.
Liquid Nitrogen Reservoir
1.0µm
890nm
Substrate Temperature Coverage Shape Size
Room Temp 97% Round/oval 268 nm
-15 °C 68%Oval, pointed
in various directions
247 nm
-30 °C 88% Round, slanted 223 nm
-80 °C 75%Needle shaped,
random orientation
251 nm
Best surface at various substrate temperature was -30 °C.At -30 °C 3-HPLN covers 88% of the surface but has a
roughness of 50 nm. A comparison of Croconic acid and 3-HPLN found that
Croconic acid had a smoother surface, with 97% Coverage and 3.5nm Roughness.
Substrate
By using the AFM, we obtained the images of the surface of the
thin films to analyze how various sub. Temperatures effected the
morphologies