1. A Study of the Growth Conditions of ZnO Nanowires by
Pulsed Laser Deposition
E. Acosta, R.A. Rodriguez-Davila, M.A. Quevedo-Lopez
Department of Materials Science and Engineering, University of Texas at Dallas, 800 W.
Campbell Drive, RL 10, Richardson, TX 75080

2. Abstract
ZnO nanostructures grown on Si(100) by pulsed laser
deposition. The morphology of ZnO depended on the
conditions used for deposition. With increasing pressure the
nanostructures are seen to be separating while the
temperature is controlling the growth. The nanowires are best
grown in the following temperatures of 700-800 ºC. The ZnO
nanowire growth was examined using the scanning electron
microscope (SEM). Using a longer deposition time, we were
able to increase the height of the nanowires. The condition
that grew the best result was at a temperature of 800 ºC and
pressure of 1 Torr with 75k shots. Though this is the best
condition, the growth of the nanowires do not follow the same
trend of the effects of temperature and pressure at 800 ºC
compared to 600-700 ºC. Using a two-step procedure involved
depositing a seed layer at low temperature with further
deposition at higher temperature we were able to conclude
that the nanowires are to clustered and dense using this
process.

3. ZnO Nanowires Background
Zinc Oxide (ZnO) is a semiconductor used in
many applications do to its unique material
properties and great performance in
electronics, optics, solar cells and photonics.
Some of the beneficial properties of this
compound is the fact that ZnO contains a
wide bandgap of ~3.37 eV making it ideal
for UV applications.
Fig. 1 SEM image of Nanowires
Fig. 2 Nanowires Solar Cell Structure
Susner, M.A. (2014). “Catalyst-free ZnO nanowires on silicon by pulsed laser deposition with tunable density
and aspect ratio.” Physica E (Columbus, OH) 62: 95-103.

4. Pulsed Laser Deposition (PLD)
A thin film deposition technique where
a high power pulsed laser beam is
focused inside vacuum chamber to
strike deposited material. Material is
vaporized from target which is
deposited in thin film on a substrate.
Fig. 3 Schematic of the how
deposition technique
process works
Fig. 4-7 Krypton Flouride laser, laser optics, oxide chamber, ZnO deposition

5. Experimental Set Up
Energy Density Calibration
13 14 15 16
0.6
0.8
1.0
1.2
1.4
1.6
EnergyDensity(Joule/cm)
Distance (cm)
Energy Density
Linear Fit
95% CI
Fig 8. Spot size for
calculating energy densitySet Energy density at 1 J/𝒄𝒎 𝟐
Calculated Focal Distance 14 cm
The energy density ranges from 0.8-1.1 J/𝑐𝑚2

6. Deposition Conditions
600 C 700 C 800 C
500 mTorr 500 mTorr 500 mTorr
1 Torr 1 Torr 1 Torr
5 Torr 5 Torr 5 Torr
Analyze using
SEM

7. Results

10. Increased deposition time (more shots) for best
condition at a frequency of 5 Hz

11. 2 Step Process (using seed layer)

13. Growth maps of pressure and temperature for
ZnO nanowire growth between 600-800 ºC
600 650 700 750 800
1
2
3
4
5
Pressure(Torr)
Temperature (C)
46
121
196
271
346
421
496
571
646
AverageHeight(nm)
One step procedure map
600 650 700 750 800
1
2
3
4
5
Averagediameter(nm)
Pressure(Torr)
Temperature (C)
94
130
166
201
237
273
309
344
380
Two step procedure map

14. Conclusions
We have demonstrated that ZnO nanowires can be grown
using the pulsed laser deposition technique. These nanowires
will only grow in the temperature range of 700-800 ºC with
pressure range of 0.5-5 Torr. We concluded that the best
condition to grow nanowires is at 800 ºC at 1 Torr with 75k
shots.