TY - JOUR
T1 - Multi-wavelength emission through self-induced defects in GaZnO microrods
AU - Rahman, M. Azizar
AU - Ali, Sajid
AU - Phillips, Matthew R.
AU - Ton-That, Cuong
N1 - Funding Information:
This work was supported under Australian Research Council (ARC) Discovery Project funding scheme (projects DP150103317 and DP210101146 ). M. Azizar Rahman acknowledges the financial support of Australian Government through the Research Training Program Scholarship. This research was partly undertaken on the Soft X-ray Spectroscopy (SXS) beamline at the Australian Synchrotron. Theoretical calculations were conducted with resources provided by National Computational Infrastructure (NCI) as well as Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia . We thank Prof Michael Ford for useful discussions.
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/2/25
Y1 - 2022/2/25
N2 - Multi-wavelength emission in wide bandgap semiconductors is commonly achieved through ternary alloying or quantum size effects. However, multi-wavelength emission within a single microstructure is highly challenging using these approaches. Here, we demonstrate that the luminescence wavelength within individual GaZnO microrods can be tailored via defect engineering. Fast chemical vapor growth of oxygen-rich ZnO microrods with Ga2O3 as an additive in the ZnO vapour leads to formation of a tapered morphology with graded distribution of Ga dopants, while the Ga incorporation does not significantly alter their crystal structure. With increasing Ga content from 1 to 6 at% from tip to base, the GaZnO microrods increase in diameter towards the substrate in accordance with the birth-and-spread mechanism. The local near-band-edge emission within single ZnO microrods, analyzed by nanoscale cathodoluminescence spectroscopy, exhibits a red shift of ~0.6 eV with increasing Ga content and exhibits signature characteristics of an excitonic emission. Density Functional Theory calculations reveal that the variation in the emission wavelength arises from bandgap narrowing due to the merging of the electronic states of Ga defect complexes with ZnO energy bands. The experimental and theoretical results demonstrate (i) the utility of using the self-regulation of defect compensation effects for band gap engineering and (ii) the possibility of multi-wavelength light sources within individual microrods.
AB - Multi-wavelength emission in wide bandgap semiconductors is commonly achieved through ternary alloying or quantum size effects. However, multi-wavelength emission within a single microstructure is highly challenging using these approaches. Here, we demonstrate that the luminescence wavelength within individual GaZnO microrods can be tailored via defect engineering. Fast chemical vapor growth of oxygen-rich ZnO microrods with Ga2O3 as an additive in the ZnO vapour leads to formation of a tapered morphology with graded distribution of Ga dopants, while the Ga incorporation does not significantly alter their crystal structure. With increasing Ga content from 1 to 6 at% from tip to base, the GaZnO microrods increase in diameter towards the substrate in accordance with the birth-and-spread mechanism. The local near-band-edge emission within single ZnO microrods, analyzed by nanoscale cathodoluminescence spectroscopy, exhibits a red shift of ~0.6 eV with increasing Ga content and exhibits signature characteristics of an excitonic emission. Density Functional Theory calculations reveal that the variation in the emission wavelength arises from bandgap narrowing due to the merging of the electronic states of Ga defect complexes with ZnO energy bands. The experimental and theoretical results demonstrate (i) the utility of using the self-regulation of defect compensation effects for band gap engineering and (ii) the possibility of multi-wavelength light sources within individual microrods.
KW - DFT calculations
KW - GaZnO microrod
KW - Wavelength-tunable emission
UR - http://www.scopus.com/inward/record.url?scp=85119909114&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2021.162693
DO - 10.1016/j.jallcom.2021.162693
M3 - Article
AN - SCOPUS:85119909114
VL - 895
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
IS - Part 2
M1 - 162693
ER -