Characterization Of Porous Silicon And Zinc Oxide/Porous Silicon For Photodetector Application
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Date
2018-09
Authors
Nurizati Rosli
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Zinc Oxide (ZnO) is widely used for the development of optoelectronic and
electronic devices such as photodetectors, piezoelectric, field-effect transistors (FET),
light emitting diodes (LED), photovoltaic, chemical sensors and others, because of its
capability of fast response, high optical gain, high surface-to-volume ratio, and specific
crystalline orientation. Meanwhile, porous silicon (PS) has drawn much attention for
its application in the development of silicon-based optoelectronic devices due to its
adjustable surface roughness and its ability to reduce the large mismatch in the lattice
constants with the formation of porous layer. Merging both materials, the work is
carried out to synthesize and characterize the properties of ZnO growth on PS. The PS
substrates were prepared by using different parameter of etching time and current. It
was found that, the etching condition is at current of 25 mA and 15 minutes etching
time on n-type Si substrate with orientation (100) would achieve a uniform porous
surface and good optical properties. Later, ZnO was sputtered onto the PS substrate by
RF as a seed layer. The seed layer assists the nucleation of ZnO also promotes the
growth development of ZnO wurtzite crystal structure along c-axis orientation. The
different seed layer thickness of (50, 100, and 200) nm were sputtered. Then, the
growth of ZnO structure was performed using chemical bath deposition (CBD)
technique with different growth time of (1, 3 and 5) hours. Morphological analysis
show that the grown ZnO microstructures covered randomly on and into the PS
structure. With the increase in the amount of seed layer and the growth time, the higher distribution for atomic and the weight percentage of oxygen and zinc. The X-ray
diffraction (XRD) spectra indicate a high-quality growth of ZnO in lattice direction of
(100), (101) and (002). Raman scattering analysis revealed the peaks shift of E2 (High),
characterized a wurtzite lattice and indicates a good crystallinity of the ZnO. To test
the performance as a device, an MSM photodetectors (PDs) were fabricated with Ni
contact formed on the samples. The growth parameter of the samples are set as follows.
PS is formed at the etching time of 15 minutes and current of 25 mA. For ZnO, the
thickness of seed layer is 200 nm, and CBD growth time of 5 hours. A good Schottky
contact and photo-responsivity has been demonstrated from the annealed MSM PDs
test device.
Description
Keywords
Physics