ISSN 2580-0817
Journal of Mechanical Engineering Science and Technology Vol.
No.
November 2025, pp.
Effect of Argon Gas Flow Rate on Crystal Structure.
Morphology, and Optical Properties of CIGS Film for Photodetector Applications Nurul LathiAoi Fatul Chamidah1.
Fadilah Wulan Cahyani1.
I Gusti Ayu Isnaini Fatha Ramadhani1.
Erma Surya Yuliana1.
Nasikhudin1.
Safwan Abd.
Aziz2.
Nandang Mufti1,3* Department of Physics.
Faculty of Mathematics and Natural Sciences.
Universitas Negeri Malang.
Malang 65145.
Indonesia Laser Center.
Ibnu Sina Institute for Scientific and Industrial Research.
Universiti Teknologi Malaysia, 81310 Skudai.
Johor Bahru.
Malaysia Center of Advanced Material for Renewable Energy.
Universitas Negeri Malang.
Malang, 65145.
Indonesia *Corresponding author:nandang.
fmipa@um.
Article history:
Received: 30 July 2025 / Received in revised form: 23 September 2025 / Accepted: 29 September 2025
Available online 19 October 2025
ABSTRACT
CIGS material can be used as a material for photodetector applications.
The deposition of CIGS thin films remains challenging.
Generally, argon is used as a gas to bombard the CIGS material through the sputtering This study fabricated photodetectors by varying the argon gas flow rate .
-80 scc.
to investigate its effect on device performance.
XRD.
SEM.
UV-Vis, and photoresponse tests were characterized.
Structural analysis using XRD showed a weak .
diffraction peak, indicating that the resulting film was not fully crystalline, but rather consisted of a nanocrystalline phase, even partly amorphous, with small crystallite sizes.
According to the SEM analysis, the thin film thickness increased from 1.
005 m to 1.
m with increasing argon gas flow rate.
The UV-VIS characterization analysis exhibited a maximum absorbance at a wavelength of 234 nm and a band gap decreasing from 2.
43 to 2.
30 eV.
The photoresponse analysis revealed that thicker absorber layers responded more slowly to light exposure, indicating a reduction in charge carrier mobility.
The current and voltage response times were found to range from 3.
01 seconds and 2.
18 to 4.
35 seconds, respectively.
Therefore, it can be stated that argon gas flow rate significantly plays a role in the performance of CIGS thin film-based photodetectors.
Copyright A 2025.
Journal of Mechanical Engineering Science and Technology.
Keywords: Argon gas.
CIGS, flow rate, photodetector, sputtering.
Introduction Photodetectors are one of the key components in modern multifunctional technology .
which can convert optical signals into electrical signals .
, .
Devices used to detect light, typically in the form of photons, convert light signals into electrical signals that electronic circuits can then measure.
Photodetectors are widely used in a diverse range of applications, including optical communication systems, imaging devices .
uch as digital camera.
, solar cells, and scientific instruments, each tailored to different applications and performance requirements.
The different types of photodetectors include photodiodes, photoconductors, phototransistors, and photovoltaic cells.
For photovoltaic-type photodetectors, the structure of the device is very similar to that of a solar cell configuration .
Therefore, the performance of the photodetector can be optimized by utilizing semiconductor materials that have a high absorption coefficient and charge carrier .
Semiconductor materials with a high absorption coefficient are often utilized in solar cells, such as CIGS (Copper Indium Gallium Selenid.
DOI: 10.
17977/um016v9i2p464 Journal of Mechanical Engineering Science and Technology Vol.
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November 2025, pp.
ISSN 2580-0817
Currently.
CIGS has been explored beyond its conventional application in solar cells.
This p-type semiconductor has attracted considerable attention due to its promising As a p-type material used in photovoltaic applications.
Cu(In,G.
Se2 (CIGS) shows great potential as a light-absorbing layer owing to its high absorption coefficient .
and adjustable band gap energy spanning 1.
04 eV - 3.
5 eV .
The band gap in CIGS makes it easy to excite electrons because the energy required is the least.
The advantages of CIGS material, besides its high absorption coefficient, are that it exhibits a good surface recombination speed and favorable radiation properties .
CIGS thin film can be deposited through several methods.
Some of the techniques used in CIGS thin film deposition are non-vacuum methods, such as sol-gel .
, spin coating .
, spray coating, selenating, and electrodeposition .
Furthermore, vacuum deposition methods can be broadly divided into two primary categories: chemical vapor deposition (CVD) .
and physical vapor deposition (PVD) .
, .
Research on CIGS conducted by Duchlatet et al.
Using electrodeposition and selenation methods is time-consuming and less efficient.
Therefore, in this study, the deposition of CIGS involved sputtering.
Method Sputtering is a method included in the PVD in thin film deposition .
hin fil.
on a substrate, so it is widely used because it allows reasonable control of the composition of the film by adjusting the target sputtering .
, .
The growth of thin films requires relatively low temperatures and minimizing material loss during deposition.
The parameters involved in the sputtering process include time, power, temperature, pressure, gas type, and gas flow Argon gas is commonly utilized due to its large atomic mass, odorless and colorless characteristics, chemical inertness, and relatively low cost .
During the sputtering process, argon is ionized into plasma composed of electrons, positively charged ions, and neutral molecules under partial pressure within the plasma chamber.
The more positively charged electrons and ions hit the target, the more target atoms are sputtered towards the substrate, forming a thin film.
So, the more argon gas that flows, the thicker the layer will Research on CIGS by Rahmawati et al.
with the electrodeposition method produced an efficiency of 0.
04% .
Minimal results will be more efficient if applied as a photodetector.
Research conducted by Goddess et al.
, who examined the deposed CIGS layer using the spin coating, generated a voltage based on photoresponse testing, which is about 0.
012 mV .
In addition.
CIGS/CdS-based photoresponse research using a non-vacuum method conducted by Mandate et al.
produces a current value of about 0.
5 mA/cm2 .
Based on several previous studies, the generated current remains relatively low, determined by operating conditions including power, pressure, time, temperature, gas type, and gas flow A similar observation was reported by Serrar et al.
, who investigated the effect of argon gas flow rate on TiO2 materials.
However, despite several previous studies, there are still few that examine the impact of argon gas flow rate on the thickness of the CIGS layer as a photodetector in sputtering.
Therefore, this study investigated the influence of argon gas flow rate on the sputtering process, focusing on the thickness of the CIGS layer, morphology, crystal structure, optical properties, and photoresponse of CIGS films.
The composition of the CIGS film fabrication used in this study is the FTO/CIGS/ITO substrate The deposition of the CIGS layer uses RF sputtering, while the ITO layer is carried out using DC sputtering by varying the flow rate of argon gas during the deposition of the CIGS layer, which aims to determine the effect of the flow rate of argon gas on the crystal structure, morphology, and optical properties of the CIGS layer.
In addition, this study aims to study the effect of argon gas flow rate on the thickness of CIGS layers for photodetector Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology Vol.
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November 2025, pp.
II.
Material and Methods The research methodology outlines the chronological framework of the study, including the research design, experimental procedures .
resented as algorithms, pseudocode, or other format.
, instruments, and analytical techniques employed to address the research problem.
The experimental methods should be described in sufficient detail to enable replication by other researchers.
Whenever applicable, the sources of reagents and materials used in the study should also be specified.
Firstly, the FTO substrate is washed twice using an ultrasonic cleaner.
Initially, the FTO substrate is cleaned with soapy water.
It is then washed using acetone and rinsed using DI Water.
After the FTO substrate is washed, it is then dried using tissue.
Second, the deposition of the layer starts with the CIGS layer, and then the ITO is layered on it.
All thin-film depositions were performed using the sputtering technique, with the corresponding sputtering parameters displayed in Table 1.
Table 1.
Parameters of the sputtering deposition process Parameters CIGS (RF) ITO (DC) Pressure (P.
Power (W) Time .
Temperature (AC) Flow rate argon gas .
50, 60, 70, and 80 The deposition of the CIGS layer is carried out by varying the flow rate of argon gas, namely 50, 60, 70, and 80 sccm .
tandard cubic centimeters per minut.
In this study, several variables are used, including free, controlled, and bound variables.
The independent variable was the argon gas flow rate used during CIGS layer deposition, while the controlled variables included pressure, power, deposition time, and temperature.
The bound variables include crystal structure, morphology.
CIGS layer thickness, optical properties, and the sample's response to light.
Fabrication The CIGS fabrication process is carried out by deposition of 2 layers, namely the CIGS and ITO layers.
The FTO layer acts as a conductive substrate, then the CIGS layer as an absorber layer, while the ITO layer acts as a contact.
An illustration of the fabrication of the CIGS sample is shown in Figure 1.
Fig.
FTO/CIGS/ITO coating Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
Journal of Mechanical Engineering Science and Technology Vol.
No.
November 2025, pp.
ISSN 2580-0817
All thin-film depositions were carried out using the sputtering technique.
The deposition of the CIGS layer was performed by RF sputtering, whereas the ITO layer was deposited using DC sputtering under different parameter settings.
The deposition parameters are presented in Table 1.
During the deposition of the CIGS layer, variations in the argon gas flow rate were investigated at 50, 60, 70, and 80 sccm.
Characterization Characterization was performed on CIGS samples prepared under different argon gas flow rates.
X-ray diffraction (XRD) was used to determine the crystal structure, while scanning electron microscopy (SEM) was employed to examine the surface morphology and thin-film porosity.
Cross-sectional SEM analysis was conducted to measure the deposited film thickness, and energy-dispersive X-ray spectroscopy (EDX) was used to identify the elemental composition of the film surface.
Additionally, ultraviolet-visible (UV-Vi.
spectroscopy was carried out to evaluate the band gap energy and optical absorbance.
Additionally, a photodetector was tested using a solar simulator to determine the sample's response to the presence of light.
Analytical Techniques The test results in this study were analyzed using several software programs.
The OriginPro 2018 software is used to generate the graph from the results of XRD characterization, as well as the photoresponse graph of current density and voltage.
Subsequently, to analyze the thickness and surface morphology of the thin films, the ImageJ software was used.
To find the porosity value, use Origin software.
Eq.
is used to calculate the porosity value.
Porosity = Pore volume Total volume y 100% .
Band gap energy was determined using the Tauc plot equation (Equation .
) .
2 = A.
v Oe Eg ) a.
The value of represents the materialAos absorption coefficient, h is PlanckAos constant, v denotes the photon frequency, ya corresponds to the photon energy, and Eg represents the band gap energy .
, .
Results and Discussions Structural Characterization (XRD) XRD characterization was performed on four CIGS samples with varying argon gas flow rates, namely 50, 60, 70, and 80 sccm.
The results of the XRD characterization are presented in Figure 2.
In the samples deposited at lower argon flow rates .
and 60 scc.
, weak diffraction peaks corresponding to the .
plane at 27.
3 were detected, indicating the presence of very fine nanocrystals.
X-ray diffraction (XRD) analysis only shows a weak diffraction peak on the .
plane corresponding to the CIGS chalcopyrite phase.
The absence of other peaks such as .
indicates that the film has a low degree of crystallinity, with the degree of crystallinity estimated at around 20Ae30%.
The average crystallite size calculated using the Scherrer equation for the .
peak is in the range of 20Ae25 nm.
Meanwhile, at higher flow rates .
and 80 scc.
, no sharp peaks were observed, and the broad hump in the range of 2 = 25-30A suggests that the film is predominantly amorphous.
This behavior arises because higher argon pressure reduces ion bombardment energy, limiting surface diffusion of sputtered atoms and preventing ordered Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology Vol.
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lattice formation.
Consequently, films become increasingly amorphous at high flow rates.
Therefore, the crystallinity of the CIGS films can be classified as nanocrystalline at lower argon flow rates and more amorphous at higher flow rates.
This trend is consistent with previous studies that reported a decrease in crystallinity with increasing argon flow due to reduced ion bombardment energy .
and contrasts with Chamidah et al.
, who showed that higher substrate temperatures improve CIGS crystallinity by enhancing atomic diffusion.
Thus, deposition parameters that lower atomic energy .
, high gas flo.
promote amorphous structures, while those that increase energy .
, high temperatur.
favor crystalline growth .
Fig.
CIGS layer XRD yield: .
50, .
60, .
70, and .
80 sccm Morphology of the CIGS Layer The morphology of the CIGS layer was characterized using SEM.
Figure 3 displays the surface morphology and cross-sectional view of the CIGS layer with a magnification of 100,000 times at the variation in the flow rate of argon gas, namely .
50, .
60, .
70, and .
80 sccm.
Based on the figure of the three layers of the CIGS, it can be concluded that the layers deposited by the Sputtering have an even and uniform result.
In comparison to deposition carried out using the electrodeposition method, which results in a rough sample surface and non-uniform grains .
In addition, the thickness of the CIGS layer can be determined by SEM testing crosection.
CIGS layer thickness by varying the flow rate of argon gas at the moment of Sputtering, known by conducting testing cross-section.
Based on Figure .
50 sccm, .
60 sccm, .
70 sccm, .
80 sccm, the thickness of the CIGS layer with variations in flow rate of argon gas is 005 m, 1.
078 m, 1.
195 m, 1.
283 m (Table .
The results of these measurements tend to be thinner when compared to previous studies.
The flow rate of argon gas has a significant influence on film thickness and surface morphology .
The thickness of the CIGS absorber layer, according to the research conducted by Khoshsirat et al.
, is in the range of 1-4 m .
CIGS coatings should ideally have a thickness range of 1-4 m to be able to respond well to Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
Journal of Mechanical Engineering Science and Technology Vol.
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November 2025, pp.
ISSN 2580-0817
The SEM characterization results were also used to determine the porosity level based on surface morphology observations.
Figure 4 presents a three-dimensional graph illustrating the porosity distribution of CIGS thin films under different conditions.
Fig.
SEM results accompanied by yield insets cross-section on CIGS layers: .
50, .
60, .
70, and .
80 sccm Table 2.
Variation of flow rate to CIGS layer thickness .
Name sample Thickness .
CIGS 50
CIGS 60
CIGS 70
CIGS 80
Fig.
Porosity distribution of CIGS layers: .
50, .
60, .
70, and .
80 sccm Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology Vol.
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November 2025, pp.
To calculate the porosity value of the CIGS layer.
Eq.
is used.
Table 3 shows the CIGS thin-film porosity calculation results for various variations.
Table 3.
SEM analysis of CIGS thin film porosity Name sample Porosity (%) CIGS 50
CIGS 60
CIGS 70
CIGS 80
Based on the morphological analysis presented in Table 3, the CIGS 50 thin film exhibited the highest porosity of 77.
A higher porosity value indicates a larger active surface area .
The SEM characterization results shown in Figure 4 confirm that the CIGS thin film with the highest porosity has the potential to increase charge recombination.
addition, surface morphology provides information about the elemental composition of the material, as presented in Table 3.
EDX analysis was conducted to identify the types and contents of elements on the surface of the thin film .
and to ensure its purity from possible EDX analysis confirmed the presence of all CIGS elements with a non-uniform atomic The highest atomic intensity is obtained in the element Selenium (S.
This is because the band gap depends on the ratio of [G.
/([G.
[I.
) (GGI) .
Based on the results of EDX characterization, the content ratio of Ga/(In G.
was obtained for each sample, as shown in Table 4.
It can be seen that the GGI content ratio is very small compared to the results obtained by Wu et al.
when the ratio of Ga/(In G.
is about 0.
3, and the Band gap approx.
14 eV .
When the ratio of Ga/(In G.
is below 0.
3, the shift of the conductive band will be close to the Fermi energy, so that the electrons will not move to the n-type semiconductor but join the hole, thus increasing the probability of recombination .
Whereas, when the ratio of Ga/(In G.
increases, the conduction band shifts away from Fermi's energy, thus reducing the likelihood of recombination .
, .
The GGI ratio of less than 0.
3 has an effect on light absorbance.
In the CIGS system, the band gap varies with different Ga/(In G.
EDX analysis verified the presence of Cu.
In.
Ga, and Se, with Ga/(In G.
ratios ranging from 0.
10 to 0.
This compositional variation is directly related to the band gap widening observed in the optical Table 4.
Elemental composition with EDX characterization of the CIGS layer Name sample Cu (%) In (%) Ga (%) Se (%) Ga/(In G.
(%) CIGS 50
CIGS 60
CIGS 70
CIGS 80
CIGS Absorbance and Band Gap.
The optical properties, including the absorbance value and band gap, of a material are measured using Ultraviolet-Visible (UV-Vi.
Uv-Vis characterization involves the Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
Journal of Mechanical Engineering Science and Technology Vol.
No.
November 2025, pp.
ISSN 2580-0817
interaction of light with the material by varying the flow rate of argon gas.
The absorbance values of each sample are shown in Figure 5.
Fig.
CIGS Layer absorbance graph with variations of the flow rate of argon gas In the testing process, there is an interaction between the material and light with a specific wavelength .
sually in the range of 200 nm to 900 n.
, so that the UV-Vis spectroscopy instrument can measure the light absorbed, transmitted, or reflected by the sample at each wavelength .
Figure 5 shows the absorbance of the CIGS layer with variations in the flow rate of argon gas in the wavelength range of 200-800 nm.
CIGS samples deposed using a flow rate of argon gas 50 SCCM have a peak of 233 nm, 60 SCCM is at a peak of 234 nm, 70 SCCM is at a peak of 234 nm, and 80 SCCM is at a peak of 234 nm.
The flow rate of argon gas has a considerable effect on the optical properties of the thin film .
This wavelength range is consistent with the findings reported by Julie et al.
, which states that the CIGS layer has a wave absorption of about 200-1050 nm .
In the 400-600 nm wavelength range, the absorbance process of the CIGS sample is still ongoing and begins to decline in the 700 nm range.
This is in accordance with research conducted by Harith et al.
, which states that the absorption is still constant in the wavelength range of 400 to 600 nm .
In addition to calculating the absorbance values, the UV-Vis characterization results were also used to determine the band gap energy using a Tauc plot ahv 2 versus hv.
The Tauc plot method is employed to determine the band gap energy of semiconductor materials through absorbance data analysis and can be applied to both crystalline and amorphous nanomaterials .
Figure 6 and Table 5 show the Tauc plot graph ahv 2 Vs hv on the CIGS sample with variations flow rate of argon gas.
Based on Table 5, if the absorbance increases, there is a decrease in the band gap value.
The value of the band gap is important because light can be absorbed by the sample if it has an energy greater than the value of the band gap .
From the results of this study, the Band gap CIGS for all variations are in the range of 2.
30 eV to 2.
43 eV.
This is in accordance with research by Roy et al.
, which states that in the chalcopyrite alloy system Cu(In.
Ga.
(Se,S)2.
Ribbon gaps vary from 1.
04 eV to about 3.
5 eV .
The optical absorption spectrum obtained from UV-Vis measurements show a shift in the absorption edge with increasing Ga content.
The band gap values estimated using Tauc plots are in the range of 2.
30 to 2.
43 eV.
This value is higher than the theoretical prediction .
09Ae1.
12 eV for GGI 0.
10Ae0.
regarding to nanocrystalline/amorphous nature of the films, which introduces localized defects and causes band tailing, which broadens the absorption edge and shifts the Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology Vol.
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November 2025, pp.
apparent optical gap.
Furthermore, this indicates that microstructural disorder and defects strongly influence the optical response.
Fig.
Result fitting band gap .
50, .
60, .
70, and .
80 sccm Table 5.
Variations in flow rate of argon gas with maximum absorbance and value of band gap Name sample Maximum absorbance .
Band gap .
V) value CIGS 50
CIGS 60
CIGS 70
CIGS 80
CIGS Photodetector CIGS-based photodetector testing refers to the ability of a sample to detect and respond to This test is conducted to determine how quickly the sample responds to light exposure.
Photodetector testing is carried out by alternately exposing the sample to light for 10 seconds and keeping it in darkness for another 10 seconds.
This cycle is repeated with a solar simulator with an intensity of 100 mW/cmA to determine the sample's response time.
Figure 7 shows a graph of current photoresponse results with variations in the flow rate of argon gas, namely 50, 60, 70, and 80 sccm, respectively.
Fig.
Photoresponse graph of current and time relationship (I-.
of various variations flow rate Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
Journal of Mechanical Engineering Science and Technology Vol.
No.
November 2025, pp.
ISSN 2580-0817
Figure 8 shows the photoresponse graph of the current relationship to time (I-.
It is known that all samples show a good response when exposed to light on.
This is characterized by an ascending graph, while when it is not illuminated .
ight of.
it is characterized by a descending The response time of the entire sample when the light on and off is shown in Table 6.
The greater the flow rate of argon gas, the slower the light response time .
ime ris.
Fig.
Current to time relationship sample response chart Table 6 summarizes the transient response times obtained from the VAet and IAet curves, which show consistent results.
The rise time ranges from 2.
18 to 5.
01 s, while the decay time ranges 59 to 4.
52 s.
A linear increase in the rise time when exposed to light is observed, and a linear decrease in the decline time when the light is turned off.
According to Table 7, the rise time .
ight o.
is consistently faster than the decline time .
ight of.
This asymmetry can be explained by the existence of trap states within the film.
Under light-off conditions, electrons remain trapped in a stable local state, resulting in slower recombination and longer decline times.
Conversely, under light-on conditions, trapped electrons can be readily excited along with newly formed charge carriers, resulting in faster current and voltage increases.
Similar behavior was also reported by Akshana et al.
, who showed that the optical response is highly dependent on the morphology, trap density, and metal composition of the material .
Table 6.
CIGS layer current response time Name sample Light On .
Light Off .
CIGS 50
CIGS 60
CIGS 70
CIGS 80
Table 7.
CIGS layer voltage response time Name sample Light On .
Light Off .
CIGS 50
CIGS 60
CIGS 70
CIGS 80
Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology Vol.
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November 2025, pp.
Figure 8 shows the photocurrent response of devices.
In comparison with previous reports.
ZnO-based photodetectors exhibited photocurrent values of 5.
7A/cm2 .
In this work, the CIGS-based thin films demonstrated a significantly higher photocurrent of around 25.
8 A/cm2.
Similarly.
Figure 9 and Figure 10 displays the photovoltage response, where devices show 0.
mV, substantially higher than the 0.
012 mV reported for CIGS films deposited by spin coating .
These results indicated that the sputtered CIGS films studied here provide superior photoresponse characteristics in terms of both current and voltage.
Fig.
Photoresponse graph of the voltage-to-time relationship (V-.
of various flow rate variations Fig.
Voltage-to-time relationship response graph Although the developed device exhibits higher photocurrent and photovoltaic values compared to previous reports, the response time .
Ae5 .
is still slower than many state-ofthe-art photodetectors.
This behavior is in contrast to the findings of Fuad et al.
, who reported a faster response .
in CIGS photodetectors when deposition time was optimized .
In comparison.
ZnO nanorod/CuSCN-based ultraviolet photodetectors respond in the order of milliseconds .
Perovskite-based photodetectors are capable of achieving response times below 100 ms .
, and even solution-processed ZnO nanocrystalbased devices can achieve sub-microsecond responses .
The slower response in the device is because carrier transport is dominated by trap states.
Structural analysis also confirmed the presence of nanocrystalline to amorphous phases with high porosity, which introduce carrier traps and prolong the transient response time.
These findings suggest a trade-off between sensitivity and speed.
Films with high porosity or disorder can enhance steady-state photocurrent through increased light scattering Chamidah et al.
(Effect of Argon Gas Flow Rate on Properties of CIGS Film for Photodetector Application.
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and effective surface area, but result in slower temporal response.
To overcome this limitation, further optimizations such as post-deposition annealing .
n a Se atmosphere or vacuu.
, surface passivation, adjusting the absorber layer thickness, and heterojunction engineering are required.
These efforts are expected to reduce trap density, increase crystallinity, and accelerate the optical response of CIGS films.
IV.
Conclusions CIGS thin films deposited by the RF sputtering method at various argon flow rates exhibited nanocrystalline to semicrystalline structures with some amorphous phases, as confirmed by XRD, which only showed a weak .
peak with an average crystallite size of 20Ae25 nm.
SEM
analysis showed a porous surface morphology with a thickness increasing from 1.
005 m at 50 sccm to 1.
283 m at 80 sccm, while EDX results confirmed the presence of Cu.
In.
Ga, and Se elements with a Ga/(In G.
ratio of 0.
10Ae0.
The UV-Vis spectrum showed a band gap widening from 2.
30 to 2.
43 eV with increasing Ga content, higher than theoretical predictions due to the presence of nanocrystalline and amorphous phases.
Photoresponse tests showed a photocurrent of about 25.
8 A/cmA and a photovoltaic of 0.
35 mV, higher than some previous reports, although the response time .
Ae5 .
is relatively slow due to trap states and porosity.
This study was limited to the characterization of the structure, morphology, optics, and photoresponse without a more detailed analysis of electrical transport or device integration, and only used the RF sputtering method with a narrow variation of argon flow rate.
Therefore, further research is needed to explore different deposition conditions, interface engineering, and more comprehensive electrical measurements to optimize the performance of CIGS-based Acknowledgment This research was supported by DRTPM Kemendikbudristek 2024 under Grant No.
102/UN32.
1/LT/2024.
The authors gratefully acknowledge the financial support that made this work possible.
References