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Preparation and Characteristics Study of Polystyrene/Porous Silicon Photodetector Prepared by Electrochemical Etching

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Novel doped polystyrene (PS)/porous silicon (PSi) heterojunction photodetector prepared by solution cast and electrochemical techniques is proposed here. The structural and optical properties of polystyrene film and porous silicon surface were investigated using X-ray diffraction (XRD), scanning electron microscope, Fourier transformed infrared (FT-IR), and UV–Vis spectrophotometer. XRD data confirmed that the PS film was amorphous in nature and the porous silicon was nanocrystalline. The optical properties showed that the average optical transmittance and the optical energy gap of PS film were 80% and 3.2 eV, respectively. The electrical properties revealed that the electrical resistivity and mobility of the doped polystyrene film were 3 × 10⁴ Ω cm and 4.5 × 10⁻⁵ cm² V⁻¹ s⁻¹, respectively. Photoluminescence PL of porous silicon was investigated. Dark I–V characteristics revealed that the PS/PSi heterojunctions prepared with an etching time of 5 min exhibited better-rectifying properties than that of PS/PSi heterojunction prepared at 10 min. The figures of merit of the photodetectors such as spectral responsivity, external quantum efficiency, and detectivity were investigated and compared with Au/PSi Schottky photodetectors. Minority carrier lifetime of the photodetectors was measured using open circuit voltage decay method.
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Vol:.(1234567890)
Journal of Inorganic and Organometallic Polymers and Materials (2019) 29:1100–1110
https://doi.org/10.1007/s10904-019-01072-9
1 3
Preparation andCharacteristics Study ofPolystyrene/Porous Silicon
Photodetector Prepared byElectrochemical Etching
HasanA.Hadi1· RaidA.Ismail2· NahidaJ.Almashhadani2
Received: 26 September 2018 / Accepted: 1 January 2019 / Published online: 4 January 2019
© Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
Novel doped polystyrene (PS)/porous silicon (PSi) heterojunction photodetector prepared by solution cast and electrochemi-
cal techniques is proposed here. The structural and optical properties of polystyrene film and porous silicon surface were
investigated using X-ray diffraction (XRD), scanning electron microscope, Fourier transformed infrared (FT-IR), and UV–Vis
spectrophotometer. XRD data confirmed that the PS film was amorphous in nature and the porous silicon was nanocrystalline.
The optical properties showed that the average optical transmittance and the optical energy gap of PS film were 80% and
3.2eV, respectively. The electrical properties revealed that the electrical resistivity and mobility of the doped polystyrene
film were 3 × 104Ωcm and 4.5 × 10−5cm2V−1s−1, respectively. Photoluminescence PL of porous silicon was investigated.
Dark I–V characteristics revealed that the PS/PSi heterojunctions prepared with an etching time of 5min exhibited better-
rectifying properties than that of PS/PSi heterojunction prepared at 10min. The figures of merit of the photodetectors such
as spectral responsivity, external quantum efficiency, and detectivity were investigated and compared with Au/PSi Schottky
photodetectors. Minority carrier lifetime of the photodetectors was measured using open circuit voltage decay method.
Keywords Porous silicon· Polystyrene· Electrochemical etching· Photodetector
1 Introduction
Porous silicon considers as an attractive and promising
material for optical radiation detectors due to its superior
properties such as large surface to volume ratio (large aspect
ratio), high optical absorption coefficient compared to crys-
talline silicon and its energy gap can be tuned over a wide
range [13]. The reported data showed that the main char-
acteristics of porous silicon photodetector were depended
on the porous silicon properties including pore size, wall
size, porosity, and thickness [4, 5]. Heterojunctions based
porous silicon photodetectors such as CdO/porous silicon,
ZnO/porous silicon, CdS/porous silicon, SiC/porous silicon,
and CdSe/porous silicon were under extensive investigations
[610]. Heterojunction photodetectors based porous silicon
were found to have superior figures of merit compared to
those of crystalline silicon [1113]. These heterojunction
photodetectors exhibit high responsivity and detectivity at
visible and ultraviolet regions. Kim etal. [14] prepared high-
performance graphene/porous silicon heterojunction pho-
todetector with responsivity around 0.2A/W at near UV
region. High sensitivity MoS2/porous silicon heterojunction
with responsivity of 9A/W in the range (550–850)nm pre-
pared by electrochemical etching technique was reported by
Dhyani etal. [15]. Compared to the metal/porous silicon
Schottky photodetectors, the top layer of the heterojunction
has a high optical transmission which in turns enhanced the
photocurrent of the photodetector during the light absorp-
tion in the depletion region. The high optical transparency,
high electrical conductivity and flexibility were key factors
which enabled the polystyrene to be used in a wide range of
applications such as optoelectronic, electromagnetic inter-
ference and electrostatic dissipation [16]. Incorporation of
carbon and metal nanoparticles into PS matrix in order to
increase its electrical conductivity was reported [17]. In this
paper, we reported for the first time preparation and charac-
terization of doped PS/porous silicon heterojunction photo-
detectors by electrochemical etching technique. Comparison
of the optoelectronic properties of PS/PSi heterojunction
* Raid A. Ismail
raidismail@yahoo.com
1 Department ofPhysics, Education Faculty, University ofAl-
Mustansiriyah, Baghdad, Iraq
2 Department ofApplied Science, University ofTechnology,
Baghdad, Iraq
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... Electrochemical etching, where silicon as an anode and an electrolyte is etched with an external power supply and light assistance [3], is an efficient and simple way to prepare porous structures, and so it has been extensively used in many areas of research and in numerous applications. Porous silicon nanocrystalline PSi has a wide band gap as compared with bulk crystalline silicon and it is the most favorable layer in the different utilizations consequent to the unique properties such as surface area relative to volume, porosity, electrical, and optical properties [4]. The pore diameter and wall thickness of the porous silicon can be manipulated via adjusting the electrochemical etching parameters. ...
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