Direct laser micropatterning of GeSe
2
nanostructures film with controlled optoelectrical
properties†
Bablu Mukherjee,
a
Govinda Murali,
b
Sharon Xiaodai Lim,
ac
Minrui Zheng,
a
Eng Soon Tok
a
and Chorng Haur Sow
*
a
We demonstrate that a direct focused laser beam irradiation is able to achieve localized modification on
GeSe
2
nanostructures (NSs) film. Using a scanning focused laser beam setup, micropatterns on GeSe
2
NSs film are created directly on the substrate. Controlled structural and chemical changes of the NSs are
achieved by varying laser power and the treatment environment. The laser modified GeSe
2
NSs exhibit
distinct optical, electrical and optoelectrical properties. Detailed characterization is carried out and the
possible mechanisms for the laser induced changes are discussed. The laser modified NSs film shows
superior photoconductivity properties as compared to the pristine nanostructure film. The construction
of micropatterns with improved functionality could prove to be useful in miniature optoelectrical devices.
Introduction
The focused laser system has found great utility in nanoscience
research. It has a wide variety of applications ranging from
micropatterning, modication of nanomaterials, manipulation
of nanorods and creation of nanorotors using optical traps.
1–3
Scientists have recently been able to produce laser beams of size
as small as that of a virus, which could further enhance the
already proven ability of lasers to create amazing 3-D structures
in nanoarrays.
4–6
Focused laser modication has been exten-
sively employed in different materials including carbon nano-
tubes,
7
graphene oxide,
8
and CuO nanorods.
1
Nanomaterials
modied with a focused laser beam oen show varied and
tunable structural, optical as well as electrical properties.
Focused laser beam irradiation with the sample housed in
controlled gas environments further enhances the degree of
variation in experimental condition during the modication of
the materials and could have many useful applications.
9
It has
been shown that focused laser beam irradiation is able to
convert less conductive graphene oxide to more conductive
reduced form.
10
Recently Lu et al. have shown multifunctional
micropatterns fabrication on CdS
x
Se
1x
nanobelt lms using
scanning focused laser beam where the samples exhibit
modication of chemical composition. And the applications of
such modied nanobelts as a potential acid sensor and more
superior photoconductor have been demonstrated.
11
Consid-
ering its simplicity, efficiency and exibility, nanomaterial
modication with focused laser system thus appears to be an
attractive approach in nanomaterial research. Furthermore,
direct patterning of the nanomaterials using focused laser
beam has an added advantage when compared with other
patterning methods such as nanoimprinting, photolithography,
microcontact printing etc. because of minimized chemical
contamination to the sample.
12–14
Germanium diselenide (GeSe
2
) has an interesting crystalli-
zation process, which can be controlled using light irradiation
or thermal-annealing.
15
The photo-induced and thermal crys-
tallization processes of amorphous GeSe
2
lms have been well
studied using Raman spectroscopy. Thermally annealed amor-
phous GeSe
2
shows the low temperature form (LT-GeSe
2
) of
crystalline GeSe
2
, On the other hand if the amorphous GeSe
2
lm is thermally annealed at a higher temperature for longer
duration, then amorphous GeSe
2
turns into high temperature
form (HT-GeSe
2
) of crystalline GeSe
2
.
16
Similarly amorphous
GeSe
2
crystallized into HT phase rather than LT phase due to
the thermal heating and photo-induced effect caused by the
laser absorption.
17
Earlier studies on GeSe
2
focused on the
properties of GeSe
2
lms. Recently single-crystalline germa-
nium diselenide (GeSe
2
) nanostructures (NSs) have become
promising candidates for eld emission devices,
18
super-
capacitor and photodetector devices.
19,20
Single crystalline
GeSe
2
has anisotropic thermal and electronic properties.
21
Chalcogenides glasses are interesting due to their potential
in optical and photonic applications.
22
In the past decades, a
large number of studies including the structure of glassy GeSe
2
a
Department of Physics, National University of Singapore (NUS), 2 Science Drive 3,
Singapore 117542, Singapore. E-mail: physowch@nus.edu.sg
b
Department of Physics & Meteorology, Indian Institute of Technology Kharagpur,
India-721302
c
Graduate School of Integrative Sciences and Engineering, National University of
Singapore, 28 Medical Drive, 117456, Singapore
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c3ra46790b
Cite this: RSC Adv. , 2014, 4, 10013
Received 18th November 2013
Accepted 23rd January 2014
DOI: 10.1039/c3ra46790b
www.rsc.org/advances
This journal is © The Royal Society of Chemistry 2014 RSC Adv. , 2014, 4, 10013–10021 | 10013
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