1. Environmental Effects on Noise in Graphene, Graphene Oxide and Carbon Nanotube Electronic Devices
  Brett R. Goldsmith   Ye Lu   Zhengtang Luo      A.T. Charlie Johnson
University of Pennsylvania
Department of Physics and Astronomy

2. Sources of Electronic Noise
measuring current noise power
Thermal Nyquist noise (~10-24)
Instrument Noise (~10-23)
Telegraph Noise (~10-18)
1/f noise
intrinsic noise
edge states
defects
surrounding environment

3. Noise Characterization
Noise power is calculated from
the power spectrum of the current.
(using FFT)
b = 1 for most devices

4. Measurements Noise Power: Noise Amplitude: α(T) = Hooge Constant
N = number of conduction channels
SI is given by the power spectrum
of the current through the device.

5. Graphene Electronics

6. Resistance vs Temperature
measured in a high vacuum chamber, at a rate of 0.1 K/10 seconds

7. Noise Power vs Temperature - Graphene
Fit for noise power at 1 Hz.
Noise Power also does not change
much with temperature

8. Graphene – Noise Amplitude
Noise Amplitude can also be calculated using fit for noise power at 1 Hz
Lin, Avouris, Nano Lett., 2008, 8 (8), pp 2119–2125

9. Reduced Graphene Oxide
Use a strong oxidizer and rapid microwave heating to chemically exfoliate graphite
Spin cast graphene oxide solution
Reduce graphene oxide using
hydrazine
We’re using a large film of GO.
50 mm
Lou, et. al., J. Am. Chem. Soc., 2009, 131 (3), pp 898–899

10. Reduced Graphene Oxide
50 mm
Resistance has a strong temperature dependence.

11. Noise Power vs Temperature
Stronger temperature dependence of
noise power.
Sharp peaks occur at particular temperatures

12. Assigning Noise Peaks
Location of water freezing point vs. Temperature and Pressure
Enhanced noise happens where we expect water to freeze in the vacuum chamber

13. Noise Amplitude

14. CNT Network – Noise Amplitude
CNT noise amplitude changes quite dramatically with temperature.
The literature has attributed these types of noise peaks to environmental effects for a few years, even in single tubes.
Kingrey et. al. Nano Lett., 2006, 6 (7), pp 1564–1568

15. Prof. A.T. Charlie Johnson
Johnson Group UPenn
Prof. A.T. Charlie Johnson
Conclusions:
Graphene 1/f noise is weakly dependent on temperature
Reduced graphene oxide 1/f noise shows very strong dependence on temperature and the surrounding environment
Carbon nanotube 1/f noise is environmentally sensitive.
Graphene seems to be coupled to it’s surroundings more weakly than carbon nanotubes.
Dr. Zhengtang Luo
Dr. Brett Goldsmith
Dr. Sasa Zaric
Sam Khamis
Bob Johnson
Luke Somers
Ye Lu
Ryan Jones
Matthew Berck
Dan Singer
Nicholas Kybert
Thomas Ly
Thanks to:
IC Postdoc
DARPA
ARO