Abstracts Book - IMRC 2018

• SA6-P045
POOLE-FRENKEL CONDUCTION MECHANISM ON SINGLE ZnO
NANOBELTS.
Karime Carrera 1 , Eduardo Murillo 2 , Ignacio Rivero 3 , Manuel Herrera 1
1 Centro de Nanociencias y Nanotecnología CNyN-UNAM, Física, Mexico. 2 Centro de
Nanociencias y Nanotecnología CNyN-UNAM, Nanoestructuras, Mexico. 3 Instituto Tecnológico
de Tijuana, Centro de Graduados, Mexico.
Currently, the main theme in nanoscience and nanotechnology is to develop simple
methods to synthesize ultrathin nanostructures being able to manipulate these
materials and exploring novel electrical properties to enable high-density device
integration taking advantage of the confinement properties. ZnO nanostructures
are attractive due to their variety of morphologies and availability of low-cost and
straightforward processing such as Thermal Evaporation (TE) technique. In this
work, we report the optimization of ZnO nanobelts synthesis by TE and
demonstrate that its defect structure dominates their electrical conductivity
properties. The synthesis of ZnO nanobelts took place in a horizontal TE furnace
onto ZnO ceramic substrates at 600°C, by using N 2 as a carrier gas with a flow
between 3.0 - 3.2 sccm. Cathodoluminescense (CL) measurements showed two
bands centered at 3.2 and 2.5 eV, attributed to the ZnO band edge and oxygen
vacancy-related emissions, respectively. Scanning Electron Microscopy (SEM)
images revealed the presence of pinholes and folds on the surface of the nanobelts,
which was confirmed using Atomic Force Microscopy in Conducting mode (C-AFM).
Leakage current (LC) images obtained with a forward bias of 5V reveal the
generation of signal contrast at some pinholes and grain boundaries regions. I-V
curves acquired for the electrical conduction through the cross-section of the
nanobelts showed a Poole-Frenkel mechanism. Electrical conduction along of
individual ZnO nanobelts was studied by using a micromanipulator, coupled in the
vacuum chamber of the SEM, composed of two In/W microelectrodes. I-V curves
acquired at bias lower than 13 Volts confirmed a Poole-Frenkel electrical
mechanism. Several I-V curves obtained at bias between -10 and 10 V permitted us
to calculate the sheet resistivity of nanobelts, recording values between 5 to 7 Ω-
cm.
Acknowledgment: This work was supported by DGAPA-UNAM (project No.
IN101917), Mexico. Technical help I. Gradilla, F. Ruiz and E. Aparicio is greatly
appreciated.
Keywords: ZnO, C-AFM, Cathodoluminescence
Presenting authors email: krrera8@gmail.com