Porous silicon (PS) photodetectors (PDs) have attracted interest for Ultra-violet (UV) detection due to their unique properties, many devices still suffer from low sensitivity and slow response. However, enhancement via silver nanoparticle (Ag-NP) modification on double-layer PS remains insufficiently studied. This work addresses this gap by using optimized spray pyrolysis method to deposit Ag-NPs, improving sensitivity and response times. Double-layer PS structures were successfully fabricated using electrochemical anodization process on p-type (111) silicon (Si) wafer, yielding average thicknesses of 9.77 µm (upper) and 9.22 µm (lower) with 33.32 nm pore diameters, offering a high surface area for optoelectronic applications. Fourier-transform infrared spectroscopy (FTIR) tests showed the presence of Si–H₂ (906, 2113 cm⁻1) and Si–O-Si (1064 cm⁻1) vibrations, and X-ray diffraction (XRD) revealed a clear peak at 2θ = 69.21°, which matches the (400) Si plane, confirming that PS was created. Ag-NPs were synthesized via laser ablation in liquid, producing uniform particles (~ 16.25 nm by Field emission scanning electron microscopy (FESEM), and 16.74 nm by XRD), which were evenly deposited onto double-layer PS. After deposition, Ag-NPs grew to 20.55 nm, and PS’s thicknesses slightly increased to 10.24 µm (upper) and 9.41 µm (lower), confirming successful infiltration. Energy dispersive X-ray spectroscopy (EDS) confirmed 2.26% Ag incorporation and reduced Si content, suggesting surface oxidation. According to Photoluminescence (PL) test, When PS excited with 375 nm light, it emitted red light at 719.82 nm (bandgap 1.72 eV), showing it has tiny crystal areas, and after adding Ag-NPs, it shifted to blue light at 469.81 nm (bandgap 2.64 eV), indicating better quantum confinement and light emission. Graphite, used as electrodes, provided stable and good ohmic contact, while thermal annealing at 130 °C for 30 min improved the adhesion and stability of the electrode contacts. The performance of the PDs based on PS and PS- Ag-NPs was evaluated under 395 nm UV illumination at various voltage levels ranging from -5.2 V to + 5.2 V and light intensities of 1, 2, 3, 5, 7, 10, and 12 mW/cm2. Sensitivity and responsivity were recorded at ± 2.8 V, ± 4 V, and ± 5.2 V. At + 5.2 V, PS-Ag-NPs reached 62.36 µA photocurrent, 3445% sensitivity, and 1.033 A/W responsivity, outperforming PS (6.4 µA, 902%, 0.102 A/W). At -5.2 V, PS-Ag-NPs showed even better results (-67.15 µA, 3882%, 1.045 A/W) compared to PS (-7.12 µA, 1130%, 0.099 A/W), and similar patterns were seen at lower voltages. I-T measurements of the PS- Ag-NPs device showed that at + 5.2 V, the rise time decreased from 287 μs to 168 μs with increasing irradiances, due to faster photocarrier generation. Conversely, fall time increases from 146 μs to 254 μs, attributed to carrier trapping and delayed recombination at higher irradiance levels. These improvements come from the way double-layer PS absorbs light, the special effects of Ag-NPs, and stronger Schottky barriers, making it a very sensitive UV PD that can be used in advanced electronic and sensing technologies.

Plasmon Enhanced UV Photodetector Utilising Silver Ablated Silver Nanoparticle on Double Porous Silicon Layers

期刊论文
发表日期：

2025年8月30日

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Mohammed Idrees Omer,
Nasih Hma Salah

摘要

Porous silicon (PS) photodetectors (PDs) have attracted interest for Ultra-violet (UV) detection due to their unique properties, many devices still suffer from low sensitivity and slow response. However, enhancement via silver nanoparticle (Ag-NP) modification on double-layer PS remains insufficiently studied. This work addresses this gap by using optimized spray pyrolysis method to deposit Ag-NPs, improving sensitivity and response times. Double-layer PS structures were successfully fabricated using electrochemical anodization process on p-type (111) silicon (Si) wafer, yielding average thicknesses of 9.77 µm (upper) and 9.22 µm (lower) with 33.32 nm pore diameters, offering a high surface area for optoelectronic applications. Fourier-transform infrared spectroscopy (FTIR) tests showed the presence of Si–H₂ (906, 2113 cm⁻¹) and Si–O-Si (1064 cm⁻¹) vibrations, and X-ray diffraction (XRD) revealed a clear peak at 2θ = 69.21°, which matches the (400) Si plane, confirming that PS was created. Ag-NPs were synthesized via laser ablation in liquid, producing uniform particles (~ 16.25 nm by Field emission scanning electron microscopy (FESEM), and 16.74 nm by XRD), which were evenly deposited onto double-layer PS. After deposition, Ag-NPs grew to 20.55 nm, and PS’s thicknesses slightly increased to 10.24 µm (upper) and 9.41 µm (lower), confirming successful infiltration. Energy dispersive X-ray spectroscopy (EDS) confirmed 2.26% Ag incorporation and reduced Si content, suggesting surface oxidation. According to Photoluminescence (PL) test, When PS excited with 375 nm light, it emitted red light at 719.82 nm (bandgap 1.72 eV), showing it has tiny crystal areas, and after adding Ag-NPs, it shifted to blue light at 469.81 nm (bandgap 2.64 eV), indicating better quantum confinement and light emission. Graphite, used as electrodes, provided stable and good ohmic contact, while thermal annealing at 130 °C for 30 min improved the adhesion and stability of the electrode contacts. The performance of the PDs based on PS and PS- Ag-NPs was evaluated under 395 nm UV illumination at various voltage levels ranging from -5.2 V to + 5.2 V and light intensities of 1, 2, 3, 5, 7, 10, and 12 mW/cm². Sensitivity and responsivity were recorded at ± 2.8 V, ± 4 V, and ± 5.2 V. At + 5.2 V, PS-Ag-NPs reached 62.36 µA photocurrent, 3445% sensitivity, and 1.033 A/W responsivity, outperforming PS (6.4 µA, 902%, 0.102 A/W). At -5.2 V, PS-Ag-NPs showed even better results (-67.15 µA, 3882%, 1.045 A/W) compared to PS (-7.12 µA, 1130%, 0.099 A/W), and similar patterns were seen at lower voltages. I-T measurements of the PS- Ag-NPs device showed that at + 5.2 V, the rise time decreased from 287 μs to 168 μs with increasing irradiances, due to faster photocarrier generation. Conversely, fall time increases from 146 μs to 254 μs, attributed to carrier trapping and delayed recombination at higher irradiance levels. These improvements come from the way double-layer PS absorbs light, the special effects of Ag-NPs, and stronger Schottky barriers, making it a very sensitive UV PD that can be used in advanced electronic and sensing technologies.