1.  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 (110 -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
References
1 Slashgear.com
http://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, USA
2Department 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 Holder
3-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