Fabrication Of Photodetectors Research Articles

Fabrication and characterization of photodetector using solvothermally synthesized p-CZTS/Se nanocrystals and n-Si heterojunction

Fabrication and characterization of photodetector using solvothermally synthesized p-CZTS/Se nanocrystals and n-Si heterojunction

Low-temperature growth of CuS thin film on flexible substrates for photodetection

Abstract The covellite phase of copper sulfide thin film (CuS), due to its excellent electronic, optical and chemical properties, has attracted enormous attention in cutting-edge research. This is a comprehensive study of the structural, optical, morphological and electrical properties of CuS thin films deposited by chemical bath deposition technique on flexible polyethylene terephthalate (PET) substrates at different deposition temperatures, i.e. 25 °C, 40 °C, 55 °C and 70 °C for the fabrication of flexible photodetectors. X-ray diffraction and Raman spectral studies reveal the presence of hexagonal covellite phase (CuS), whereas the root mean square (RMS) roughness of CuS thin film increases with an increase in deposition temperature. The optical bandgap of CuS thin film is found to be decreased with an increase in deposition temperature. The optimized CuS thin film, deposited at 70 °C, exhibits a homogeneous surface with RMS roughness of 13.72 nm, mobility of 25.09 cm2 V−1s−1 and bandgap of 1.86 eV. The mobility of CuS thin film is found to be increased with the increase in deposition temperature. The flexible CuS photodetector, fabricated at 70 °C, exhibits better photoresponse characteristics, with the highest responsivity of 0.18 mA W−1, specific detectivity of 1.39 × 108 Jones and sensitivity of 173.25 % upon light illumination. The established photocurrent possesses an outstanding dependence on various intensities of illuminated light. Furthermore, the bending test of flexible CuS photodetectors reveals the absence of any sign of deterioration up to bending angle of 30°. This suggests that the Al/CuS-PET/Al photodetector device could be used in various wearable optoelectronic device applications.

Fabrication and Characterization of Flexible CuI-Based Photodetectors on Mica Substrates by a Low-Temperature Solution Process

Both CuI and CuI:Zn semiconductor thin films, along with MSM-structured UV photodetectors, were prepared on flexible mica substrates at low temperature (150 °C) by a wet chemical method. The two CuI-based films exhibited a polycrystalline phase with an optical bandgap energy close to 3.0 eV. Hall effect measurements indicated that the CuI thin film sample had p-type conductivity, while the CuI:Zn thin film sample exhibited n-type conductivity, with the latter showing a higher carrier mobility of 14.78 cm2/Vs compared to 7.67 cm2/Vs for the former. The I-V curves of both types of photodetectors showed asymmetric rectification characteristics with rectification ratios at ±3 V of 5.23 and 14.3 for the CuI and CuI:Zn devices, respectively. Flexible CuI:Zn devices exhibited significantly better sensitivity, responsivity, and specific detectivity than CuI devices both before and after static bending tests. It was found that, while the optoelectronic performance of flexible CuI-based photodetectors degraded under tensile stress during static bending tests, they still exhibited good reproducibility and repeatability in their photoresponses.

Influence of Temperature on the Performance of Metal Semiconductor Metal Photodetector Fabricated by Pure and Cationic Doped (Mg2+ and Cu2+) SnO2 Nanoparticles

Research based on various temperatures always provides beneficial awareness in the fabrication of a vital photodetector for significant applications. Increasing temperature and including dopants in photodetector materials will influence the functioning of the photodetector. This study included the influence of temperature on pure and doped SnO2 photodetectors. The crystal structure of stannic oxide has been modified by adding cationic dopants, namely Mg2+ and Cu2+, through co-precipitation techniques. Various characterization techniques were employed to examine the impact of Mg2+ and Cu2+ on the Sn4+ lattice. The electrical properties of the materials were studied at different temperatures using the Hall effect. Pure SnO2, Mg-doped SnO2, and Cu-doped SnO2 nanoparticles were synthesised separately and used as photodetectors using fluorine-doped tin oxide film as a conductive medium. The fabricated photodetectors are optimized by current-voltage characteristics at different temperatures. The effects of defects in crystal structure, oxygen vacancies, carrier concentration, and temperature on the photodetectors were studied. Comparative studies of pure and doped SnO2 photodetectors revealed that temperature and crystal defects play a significant role in photoconduction.

Simulation and Fabrication of Monolithic III-V Photodetectors on Si: The Role of Growth Facets and Localization of Heterojunctions

Simulation and Fabrication of Monolithic III-V Photodetectors on Si: The Role of Growth Facets and Localization of Heterojunctions

Angle-resolved polarization Raman spectroscopy of β-Ga2O3 and their application in sensitive solar-blind photodetection

Polarization-sensitive photodetection has promising prospects for civilian and military applications based on anisotropic semiconductors. However, it is greatly limited due to the lack of valid materials as well as the terrible linear dichroism ratio. In this Letter, a metal–oxide–semiconductor β-Ga2O3 with strong anisotropic property is proposed for highly efficient polarizing detection, which can potentially overcome these limitations. Angle-resolved polarization Raman spectroscopy was performed to confirm excellent anisotropic phonon vibration. Unique narrow solar-blind polarization-sensitive photo-absorption (240–270 nm) can be observed, which can be attributed to the natural anisotropy, referring in particular to the polarization-resolved absorption in the surround of the bandgap of β-Ga2O3. Benefiting from the structural anisotropy, the polarization-sensitive photodetector exhibits an excellent linear dichroic ratio of ∼1.8. Moreover, obvious color change is observed under different polarized angles, providing great potential in polarization imaging. With these advantages, we anticipated that this research will pave avenues for the fabrication of polarization-sensitive solar-blind UV photodetectors.

High-performance solar-blind UV bipolar junction phototransistor based on a vertical Pt/Ga2O3/p-Si Schottky emitter structure

Solar-blind UV photodetectors are extensively applied in both military and civilian domains. In this work, a high-performance Pt/Ga2O3/p-Si Schottky emitter solar-blind UV bipolar junction phototransistor is demonstrated. It exhibits a peak responsivity (@246 nm) of 1632.8 A/W under a bias of 5 V. This responsivity is significantly enhanced compared to the Al/Ga2O3/p-Si heterojunction photodetector, while its response speed remains largely unchanged. Additionally, the device demonstrates excellent solar-blind UV spectral selectivity, with a solar-blind UV to visible-blind UV rejection ratio (R246 nm/R365 nm) reaching 2.4×104. This work provides new insights into the design and fabrication of high-performance Ga2O3-based solar-blind UV photodetectors.

Plasmonic Particle Integration into Near-Infrared Photodetectors and Photoactivated Gas Sensors: Toward Sustainable Next-Generation Ubiquitous Sensing.

Current challenges in environmental science, medicine, food chemistry as well as the emerging use of artificial intelligence for solving problems in these fields require distributed, local sensing. Such ubiquitous sensing requires components with 1) high sensitivity, 2) power efficiency, 3) miniaturizability, and 4) the ability to directly interface with electronic circuitry, i.e., electronic readout of sensing signals. Over the recent years, several nanoparticle-based approaches have found their way into this field and have demonstrated high performance. However, challenges remain, such as the toxicity of many of today's narrow bandgap semiconductors for NIR detection and the high energy consumption as well as low selectivity of state-of-the-art commercialized gas sensors. With their unique light-matter interaction and ink-based fabrication schemes, plasmonic nanostructures provide potential technological solutions to these challenges, leading also to better environmental performance. In this perspective recent approaches of using plasmonic nanoparticles are discussed for the fabrication of NIR photodetectors and light-activated, energy-efficient gas sensing devices. In addition, new strategies implying computational approaches are pointed out for miniaturizable spectrometers, exploiting the wide spectral tunability of plasmonic nanocomposites, and for selective gas sensors, utilizing dynamic light activation. The benefits of colloidal approaches for device fabrication are discussed with regard to technological advantages and environmental aspects, which are barely considered so far.

Photoresponse properties of green-assisted Fe3O4 nanoparticles supported activated carbon

The photoresponse properties of green synthesized Fe3O4 (gFe3O4) supported-activated carbon (AC/g-Fe3O4) were studied using a photocurrent characterization approach. Preliminary UV–Vis analysis suggested a reduction in the band gap energy when activated carbon is incorporated into gFe3O4 nanoparticles (2.61 → 1.57 eV). The current-voltage characteristics indicate semiconductor features for both gFe3O4 and AC/gFe3O4 nanoparticles. The photodetector measurements indicate a significantly enhanced response for AC/gFe3O4 and can be attributed to increased rectification and photogenerated carriers emanating from the activated carbon incorporation. The study proposes AC/gFe3O4 nanocomposite as a novel material that can be used for the fabrication of photodetectors and other related optoelectronic devices.

Development of a self-powered mixed halide perovskite-based planar near-ultraviolet photodetector by leveraging the pyro-phototronic effect

Self-powered devices enabled by pyro-phototronic effect (PPE) in mixed halide perovskites was investigated, diverging from conventional approaches that focus on ferroelectric materials and single-halide compositions. The compound (C4H9NH3)2PbI2Br2 was utilized to develop, a simple planar device structure that demonstrated high detectivity in the near-ultraviolet (UV). The proposed device successfully detected photocurrent signals at zero bias voltage in the 405 nm and 532 nm wavelengths, thereby confirming the feasibility of a self-powered photodetector. Notably, the study reveals a significant enhancement in photocurrent, with an increase of up to 23 % at 405 nm, driven by the combined effects of PPE and photovoltaics phenomena present in mixed halide perovskites. These findings present a promising pathway for advancing the design and fabrication of near-UV optoelectronic photodetectors and related devices.

Brushy C-Decorated BiTe-Based Thermoelectric Film for Efficient Photodetection and Photoimaging.

Current strategies for simultaneously achieving high thermoelectric performance and high light absorption efficiency still suffer from complex steps and high costs. Herein, two kinds of amorphous thermoelectric films of n-type Bi2Te3 and p-type Bi0.5Sb1.5Te3 with high Seebeck coefficients were prepared by pulsed laser deposition (PLD) technology. In addition, C-decorated films with excellent light absorption efficiency at the junction of the thermoelectric legs were prepared by simple drop coating and reactive ion etching (RIE) method. The TE/C-RIE composite device exhibits excellent photodetection performance under the conditions of simulated natural light, monochromatic light, and high-frequency chopping. The maximum responsivity and specific detectivity of the device can reach 153.58 mV W-1 and 6.97 × 106 cm Hz1/2 W-1 (under simulated natural light), respectively. This represents an improvement rate of 85.91% compared to that of the pure TE device. Benefiting from the excellent photodetection efficiency of the device and integration advantage of PLD technology, the composite structure can be expanded into integrated photoimaging devices. The accurate identification of patterned light sources with letters (T, J, and U) and digitals (0-9) was successfully realized by associating the response electrical signals of each electrode with the position coordinates. This work provides valuable guidance for the design and fabrication of wide-spectrum photodetectors and complex optical imaging devices.

(Invited) MoS2 Photodetectors for Near-Infrared Biosensing Applications

Device researchers have been actively developing novel diagnostic biosensors using metallic nanoparticle-based plasmonic immunoassays.[1] In these biosensing devices, photodetectors with high photoresponsivity and low internal noise levels are integrated to detect the marginal optical signals change induced by biomarker binding events (i.e., Antigen-antibody binding). Recently, atomically thin layers of molybdenum disulfide (MoS2) have been integrated with plasmonic components to enable fast and sensitive colorimetric monitoring of disease-related biomarkers.[2] However, such biosensors are mostly operated in the ultraviolet/visible range, which needs a purification step to separate out a variety of unwanted biomaterials that absorb visible light and takes several hours of preparation steps. Thus, it would be amenable to develop biosensors for biomolecular detections or immunoassays in the whole blood (WB) analytes without any sample preparations.[3] To address the issues mentioned above, recent studies have demonstrated the engineered gold nanoparticles (AuNPs) that have localized surface plasmonic resonance (LSPR) shift around near-infrared (NIR) wavelength region. However, a high-sensitivity photodetector under NIR region is still required to detect marginal signal changes due to the target biomarker binding events. Meanwhile, the MoS2 material has been reported to exhibits superior photo-response characteristics.[4] MoS2 is a transition metal dichalcogenide material of which single- and multi-layer films exhibit an efficient electron-hole pair generation rate under photoexcitation and therefore high photo absorption as compared to silicon. Therefore, a systematical study on MoS2 photoconductors to optimize the optoelectronic properties under near-infrared (NIR) (λ = 650 nm) operation can enable zero-preparation WB immunoassays combined with specially engineered AuNPs.In this work, we study the photo-response properties (i.e., Photoresponsivity spectrum) of in-plane MoS2 photodetectors as the function of their geometric dimensions and fabrication conditions. Recent study shows that an annealing temperature after exfoliation can etch the upper layers of MoS2 flakes and clean stains on the device and therefore improve device performances (e.g., mobility). [5] This work enables the NIR operation capabilities of plasmonic colorimetric biosensing by introducing the optimized MoS2 photodetector fabrication practice. This approach reduces assay preparation times and mitigate background interference even with WB analytes and thereby enable the WB point-of-care immunoassays.

Fabrication and characterization of a visible photodetector based on a germanium/n-type silicon heterojunction using thermal evaporation deposition

Fabrication and characterization of a visible photodetector based on a germanium/n-type silicon heterojunction using thermal evaporation deposition

Low-temperature fabrication of lead-free Ag2BiI5 perovskite photodetector with excellent weak light detection ability for accurate gesture recognition

In recent years, lead halide perovskites have been extensively researched in the optoelectronics field due to their excellent optical and electrical properties, while the inherent toxicity and instability of lead halide perovskites have hindered their commercialization. Stable, lead-free perovskites as a substitute of the Pb-based perovskites show great attention. Herein, the green antisolvent diethyl carbonate is introduced to realize the low-temperature fabrication of nontoxic perovskite Ag2BiI5. The Ag2BiI5 perovskite photodetector (PD) shows excellent performance with a detectivity of as high as 1.13 × 1013 Jones and a linear dynamic range (LDR) of 147 dB. Besides, the weak light with the light intensity of as low as 18.3 nW/cm2 can be detected by our PD. Moreover, the flexible PDs are also prepared with this low-temperature process, which shows good device performance with stable bending resistance characteristics. Based on the excellent optoelectronic properties of the Ag2BiI5 PDs, a gesture recognition system is built which can realize rapid and accurate gesture recognition under ordinary indoor light, with an accuracy of 98.35 %. Our research provides new insights for the development and application of green and environmentally friendly perovskite PD.

Flexible UV photodetector based on graphite/titanium dioxide through facile transfer of pencil drawn graphite films on desired substrates

Assembly of graphite structures through pencil drawn method is considered among the most facile and inexpensive approaches for a wide range of electronic and optoelectronic applications. However, the typical limitation of this methodology is that the films and structures can be drawn on a very limited number of substrates. Here, we report a novel methodology for the transfer of pencil drawn graphite films on desired substrate. The graphite films are transferred from cellulose paper, textile and wood paper onto flexible and transparent acrylic tape. The novel wood paper substrate is also used for the fabrication of bar device using a mask which is then transferred onto the acrylic tape. TiO2 nanoparticles paste is coated on the surface of transferred bar device. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and UV–visible spectroscopy of graphite and graphite/TiO2-NPs electrodes are performed respectively to study their morphological, compositional, structural and optical features. The fabricated device acts as a UV photodetector and delivers a photocurrent as higher as 197.68 μA, photoresponsivity of 8.94 mA W−1, detectivity of 4.16 × 109 Jones at bias voltage of 5 V, response time of ∼860 ms and recovery time of ∼890 ms. The flexibility of the demonstrated photodetector is evaluated through recording changes in photocurrent under bending positions from 0 to 150°, and after employing bending cycles up to 1000. The results show that the fabrication of photodetector is facile and low-cost, and it offers valuable working compatibility under bending strains. Moreover, the flexibility of photodetectors enables their effective integration with human skin and clothes for human health monitoring applications.

Design of Next‐Generation Tin‐Based Perovskite Photodetector with Enhanced Spectral Responsivity for Eco‐friendly Applications

This study introduces an environment‐friendly perovskite photodetector (PPD) utilizing the inorganic–organic perovskite CH3NH3SnI3 as the light‐absorbing layer. Perovskite materials, known for their exceptional optoelectronic properties, hold significant promise in photodetector fabrication. The proposed device architecture strategically employs NiO and TiO2 layers to facilitate efficient hole and electron transport. The CH3NH3SnI3‐based PPD demonstrates outstanding quantum efficiency across the visible spectrum, extending into infrared regions. It exhibits a responsivity of 0.68 A W−1 and a detectivity of 3.81 × 1013 Jones. Comprehensive defect and temperature analyses are performed to understand the behavior of the proposed device. These results underscore the potential of less toxic perovskite alternatives for high‐performance photodetectors. All simulations are conducted using the SCAPS‐1D simulator to ensure the validity of the findings.

Fabrication of hybrid organic and inorganic photodetector

Fabrication of hybrid organic and inorganic photodetector

Quasi-Van der Waals Epitaxial Growth of γ'-GaSe Nanometer-Thick Films on GaAs(111)B Substrates.

GaSe is an important member of the post-transition-metal chalcogenide family and is an emerging two-dimensional (2D) semiconductor material. Because it is a van der Waals material, it can be fabricated into atomic-scale ultrathin films, making it suitable for the preparation of compact, heterostructure devices. In addition, GaSe possesses unusual optical and electronic properties, such as a shift from an indirect-bandgap single-layer film to a direct-bandgap bulk material, rare intrinsic p-type conduction, and nonlinear optical behaviors. These properties make GaSe an appealing candidate for the fabrication of field-effect transistors, photodetectors, and photovoltaics. However, the wafer-scale production of pure GaSe single-crystal thin films remains challenging. This study develops an approach for the direct growth of nanometer-thick GaSe films on GaAs substrates by using molecular beam epitaxy. It yields smooth thin GaSe films with a rare γ'-polymorph. We analyze the formation mechanism of γ'-GaSe using density-functional theory and speculate that it is stabilized by Ga vacancies since the formation enthalpy of γ'-GaSe tends to become lower than that of other polymorphs when the Ga vacancy concentration increases. Finally, we investigate the growth conditions of GaSe, providing valuable insights for exploring 2D/three-dimensional (3D) quasi-van der Waals epitaxial growth.

Development of a broadband photodetector utilizing ZnO nanorods with grating structure fabricated via nanoimprint lithography

Nanoimprint lithography (NIL) has emerged as a powerful technique for integrating nanostructures into semiconductor devices, particularly optoelectronic devices such as solar cells, light-emitting diodes (LEDs), lasers, and photodetectors (PDs). This study presents the successful fabrication of nano-patterned ZnO nanorods (ZnO NRs) using NIL, resulting in a grating structure with a linewidth of approximately 600 nm and a periodicity of around 1080 nm. Morphological characterizations, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and laser confocal microscopy, reveal well-defined grating structures with ZnO NRs deposited on the substrate. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) further confirm the crystallinity of ZnO NRs, both with and without NIL treatment. X-ray photoemission spectroscopy (XPS) shows that the NIL-patterned samples with ZnO NRs exhibit fewer defects, attributed to the O2 plasma treatment during the NIL process. The NIL-defined grating structure of ZnO NRs is then employed in the fabrication of photodetectors, which demonstrate higher sensitivity than the pure ZnO-NRs-based PDs, presumably due to the reduce defects. Moreover, the NIL-defined PDs exhibit broadband photoresponses across the UV and visible light spectrum. This work introduces a novel device design for photodetectors and highlights the potential of NIL in creating broadband ZnO-based PDs, promising applications in future optoelectronics.

Fabrication and Properties of Tungsten-doped Indium Oxide Ultraviolet Photodetector

Fabrication and Properties of Tungsten-doped Indium Oxide Ultraviolet Photodetector