UV Photodetector Applications Research Articles

Enhanced UV photodetector using Mg-doped ZnO sub-micro tube films synthesized through laser-assisted chemical bath growth

This study presents the fabrication of MgxZn(100-X)O thin films (TFs) with Mg concentration levels (x) of 0.5 at%, 1.0 at%, 1.5 at%, and 2.0 at% on glass substrates using the novel laser-assisted chemical bath growth (LACBG) method, aimed at investigating their photo-response for potential UV photodetector applications. Utilizing a continuous wave semiconductor laser with a 444.5 nm wavelength, 1 W power, and 6 min of irradiation, the LACBG method successfully produced high-quality Mg-doped ZnO TFs. These films were deposited on glass substrates coated with silver (Ag) to serve as electrode contacts for constructing a metal-semiconductor-metal (MSM) UV photodetector. The structural, optical, and electrical properties of the TFs were thoroughly analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to examine the crystal microstructures and surface morphologies, revealing vertically aligned hexagonal symmetrical sub-micro tubes. In contrast, energy dispersive X-ray (EDX) analysis confirmed successful Mg incorporation into the ZnO lattice. UV–visible absorbance spectra indicated a blue shift in the absorption edge and increased band gap energy from 3.24 eV to 3.67 eV with rising Mg content. The UV photodetectors, particularly those with 2.0 at% Mg-doped ZnO TFs, demonstrated significantly enhanced UV responsiveness attributed to optical confinement, high surface-to-volume ratio, and superior structural quality. Performance metrics for the 2.0 at% Mg-doped ZnO TFs included a responsivity of 10.60 A/W, external quantum efficiency of 34.10, specific detectivity of 2.25 × 107 Jones, noise equivalent power of 5.34 × 10−11 W, rise time of 86.9 ms, and decay time of 324.4 ms. These findings underscore the potential of Mg-doped ZnO TFs for high-performance UV photodetection applications. The novelty of this study lies in utilizing LACBG to achieve high-quality Mg-doped ZnO TFs, offering a cost-effective, low-temperature method that enhances UV photodetector performance.

Influence of AZO buffer layer on characteristics of ZnO film on glass substrates for Schottky UV photodetector applications

An Al-doped ZnO (AZO) thin film was introduced into the structure of Ag/ZnO schottky Photo detectors (PDs) prepared by magnetron sputtering method on glass substrates. Influences of AZO layer on characteristics of ZnO film and performances of Ag/ZnO schottky PDs were discussed in detail. Results investigated by means of the scanning electron microscopy (SEM), X-ray diffraction (XRD) and Photoluminescence (PL) spectra show that the introduction of an AZO buffer layer can effectively decrease the defects and improve the crystallization of the ZnO thin film. Compared with Ag/ZnO schottky PDs, the Ag/ZnO/AZO PDs possess more excellent rectifying characteristics, the photocurrent (Iph) to dark current (Id) ratio are improved from 6.4 to 100.7. Given the bias voltage at -2 V, the photoresponsivity R and detectivity D* are increased from 0.15 A W-1 to 4.08 × 1010 Jones to 0.69AW-1 and 3.78 × 1011 Jones, respectively. The response speed becomes faster, the response and delay times are decreased from 281 to 395 ms to 178 and 300 ms, respectively. The results provide a new idea for the preparation of high performance ZnO film UV PDs on low-cost glass substrates.

Investigation into epitaxial growth optimization of a novel AlGaN/GaN HEMT structure for application in UV photodetectors

Investigation into epitaxial growth optimization of a novel AlGaN/GaN HEMT structure for application in UV photodetectors

Dynamical stability, electronic and optical properties of AcAlO3 perovskite using mBJ and hybrid functionals: A DFT approach

The structural, elastic, electronic, and optical properties of perovskite AcAlO3 were examined using DFT. First, the dynamical stability of the crystal in the cubic phase was ensured by the phonon dispersion curves. The elastic moduli suggest that the perovskite is mechanically hard and brittle. The 3D elastic moduli surfaces signify moderate elastic anisotropy. To precisely predict the band gaps, the band structures are analyzed using mBJ and YS-PBE0 screened hybrid functionals. Both mBJ and hybrid schemes offer similar band structures with direct band gaps of about 5.6 eV. The optical absorption in the perovskite is prominent in the UV-C region due to the ultra-wide band gap nature and may find suitable application in deep UV photodetectors.

Synergistic Optimization of Europium‐Doped Yttria for Photoluminescence and Triboelectric Nanogenerator Applications

In recent years, multifunctional applications of the same material have gained wide recognition in various fields. The present study reports the synthesis, characterization, and multifunctional applications of europium (Eu)‐doped yttrium oxide (Y2O3) nanophosphor. Synergistic optimization of Eu‐doped Y2O3 results in enhanced photoluminescence (PL) and triboelectric nanogenerator (TENG) performance. Eu‐doped Y2O3 nanophosphors are synthesized using an autocombustion method, and comprehensive characterizations are conducted. The investigations indicate that the Eu doping significantly influences the PL intensity, with the highest emission observed at 3 mol% for powders. The synthesized nanophosphors are blended with silicone to fabricate hybrid films, which are utilized for energy harvesting applications using TENG technology. The TENG devices fabricated with these hybrid films demonstrate a notable relationship between the Eu concentration and the electrical output, achieving peak performance at 1 mol% Eu doping. The maximum output voltage of ≈535 V, short‐circuit current of ≈38 μA, and power density of 800 mW m−2 are observed. Further, TENG is demonstrated in a self‐powered UV photodetector application. The present results contribute to the improvement of sustainable energy technologies and open up a new window for multifunctional materials.

Fabrication of Bi-doped In2S3 thin films for highly sensitive UV photodetector applications

Fabrication of highly sensitive, high-speed photodetectors, especially using cost-effective and less toxic materials, has attracted continuous attention due to their outstanding advantages. In this report, we present different properties of Bi-doped (0,1, 3, and 5 wt%) In2S3 thin films for UV photodetectors. Bi-doped (0, 1, 3, and 5 wt%) In2S3 thin films were coated on glass substrates at a temperature of 350 °C using a low-cost nebulizer spray pyrolysis method. X-ray diffraction XRD analysis confirmed the cubic phase β-In2S3 for all the deposited films and high crystallinity is obtained for 1 wt% Bi-doped film. The presence of densely packed grains in 1 wt% Bi-doped In2S3 thin film and also small grains observed for undoped In2S3 sample is evident form morphology studies. Bi doping has caused an enhancement of optical absorption and incorporation of 1 wt% of Bi3+ into In2S3 has shifted the optical band gap from 2.87 to 2.78 eV. Current − Voltage characteristics and Current–Time characterization are used to know the key parameters of the photodetectors. Among all fabricated photodetectors, the In2S3 thin film doped with 1 wt% Bi showed superior photodetector performance with calculated Responsivity (R), Detectivity (D*), and External quantum efficiency (EQE) values of 0.65 AW−1, 15 × 1010 Jones, 125 % respectively. Transient photo-response analysis showed low rise and fall time of 3.21 and 3.78 s respectively for the 1 wt% Bi-doped sample. Optimally doped In2S3: Bi (1 wt%) thin film is most suited to fabricate photo sensing-based optoelectronic devices in UV region of the spectrum.

Testing the physical properties stability of Zinc (8-hydroxyquinoline) thin films toward stable photodetection performance: Effect of annealing

In this study, the effect of thermal annealing on the structural and optical properties of thermally evaporated zinc (8-hydroxyquinoline) (ZnQ2) thin films is discussed in detail. Differential scanning calorimetry analysis revealed the thermal stability of the ZnQ2 powder up to 540 K. Fourier transform infrared spectrometer characterizations revealed the stability of the ZnQ2 molecular structure up to 423 K. The annealing effect on the surface morphology of the ZnQ2 films was tracked using the field emission scanning electron microscope (FE-SEM) technique, which revealed grain growth up to 423 K achieving the highest surface smoothness. Moreover, UV–Vis-NIR spectrophotometric measurements were used to examine how annealing affects the optical characteristics of the prepared films. The optical bandgap of ZnQ2 augmented when the annealing temperature increased to 373 K. The dispersion parameters were estimated from the analysis of the complex refractive index following the single oscillator model. The behavior of nonlinear optical susceptibility suggested the validity of utilizing ZnQ2 thin films in IR and UV optical switching applications and UV photodetection applications.

Influence of deposition temperature on the defect mediated persistence photo-conducting behaviour of spray coated Zn0.96Nd0.04O thin films

The incorporation of Neodymium into ZnO lattice enhances the photo conducting property of the deposited films which are strongly dependent on preparation conditions. Hence, the comprehensive work carried out to understand the influence of deposition temperature (300 °C–500 °C) on the persistence photoconductivity of Zn0.96Nd0.04O films deposited on glass substrates using spray pyrolysis method. The maximum crystallite size of ∼16.3 nm with minimum dislocation density and strain values were noticed for the films deposited at 450 °C. The mixed fibrous -granular morphology was noticed in the deposited films. The maximum transparency above 90 % in the visible region and an increased bandgap of 3.42 eV was observed in the films deposited at 450 °C. The percentage of defects were calculated using the area under the curve of photoluminescence spectra. The charge carrier density of 1.7 × 1017 cm−3, mobility of 62.8 cm2/Vs and lesser resistivity of 1.3 × 102 Ω cm were noted for the films deposited at 450 °C. Under the illumination of UV light, the photocurrent of Zn0.96Nd0.04O films deposited at 450 °C increased by four orders. The persistence in the photo resistance was due to the presence of Zn and O related defects, which acts as trap centres. The variation of photo resistance with time indicates the films deposited at 450 °C has faster photo response due to the faster electron – hole recombination process. The maximum photocurrent at 360 nm was noted for the films synthesized at 450 °C due to improved crystallinity with stoichiometry nature of the films. Hence, the Zn0.96Nd0.04O films deposited at 450 °C suitable for light dependent resistor and fixed wavelength UV photodetector applications.

Fabrication of TiO2 nanoparticles/porous-silicon heterostructure photodetector for UV detection

TiO2 nanoparticles/porous-silicon heterostructure (TiO2-NPs/P-Si) was successfully synthesized using laser-assisted chemical bath deposition (LACBD). We employed a laser of 465 nm in wavelength, output power of 1 W, and 20 min deposition time to grow TiO2 nanoparticles on porous silicon. The TiO2-NPs/p-Si films properties were characterized by using FESEM, EDX, XRD, and UV-Vis. The TiO2-NPs/P-Si/Ag photodetector device performance were examined by Keithley 2400. The I-V curve of the device was tested in dark and with UV light of 365 nm wavelength conditions. It’s I-V behavior shows a Schottky behavior in the range of − 5 V and 5 V, with strong responsiveness and excellent performance. When the device is exposed to UV light, the channel current increases drastically by 183% at + 5 V, giving rise to a pronounced photoresponse. Under UV light, the current was observed to rose from − 3.5 × 10−5 A to − 3.0 × 10−5 A at − 5 V reversed bias voltage. The current increases immensely from 1.5 × 10−5 A to 3.5 × 10−4 A at +5 V forward bias voltage. For the I-t behavior, bias voltages of 1.5 V, 3 V, 4.5 V and 6 V were used and the device responsivity at these voltages were calculated to be 0.15e-3A/W, 1.59e-3A/W, 2.05e-3A/W and 2.06e-3A/W, demonstrating a great sensitivity of 558, 1160, 758 and 458 respectively. Our findings proved that TiO2 np/p-Si/Ag based photodetector could be fabricated using inexpensive, quick, and simple LACBD and yielded an excellent electrical response and sensitivity for UV photodetection applications.

Monitoring of UV-A radiation by TiO2/CdS nanohybrid along with the high on-off ratio

Exposure to UV-A light can have detrimental effects on human health, leading to skin damage and an increased risk of skin cancer. In this study, we employed a hydrothermal-assisted method to cultivate TiO2-decorated CdS nanorods for use in UV photodetectors. Our research culminated in the fabrication of an exceptionally responsive and rapid photodetector based on the TiO2/CdS nanohybrid. X-ray diffraction analysis revealed the hexagonal phase of CdS nanorods, predominantly oriented along the (002) plane, and the presence of the anatase phase of TiO2. Scanning electron microscopy (SEM) measurements confirmed the nanorod structure of TiO2/CdS. Optical properties of the TiO2/CdS nanohybrid were investigated through UV–visible absorbance analysis. Additionally, X-ray photoelectron spectroscopy (XPS) provided insights into the surface composition of the prepared nanohybrid, with peaks corresponding to Cd 3d3/2 and Cd 3d5/2 at binding energies of 411.47 eV and 404.73 eV, respectively, and confirming the presence of titanium through peaks of Ti 2p3/2 and 2p1/2 at binding energies of 458.31 eV and 463.8 eV, respectively. Raman analysis indicated the presence of the anatase phase of TiO2 in the composite. Our device exhibited an impressive detectivity of 9.9 × 1012 Jones, an EQE (external quantum efficiency) of 971.36%, and a high photoresponsivity of 2.86 A/W. These results suggest that TiO2/CdS nanohybrids, prepared using a cost-effective and straightforward method, hold promise for UV photodetection applications.

Effect of molar concentration on optoelectronic properties of NiO nanoparticles for p-n junction diode application

In this work, fine nickel oxide nanoparticles (NiO NPs) were successfully made utilizing a straightforward co-precipitation approach at low temperature. The effects of precursor concentration on the structural, optical, and electrical characteristics of NiO nanoparticles were investigated. All indexed diffraction peaks in XRD demonstrate the production of NiO with cubic structure. An increase in NiO crystallite size above 16.8 nm was observed when the precursor concentration exceeds 2 M, suggesting the presence of nanostructure in the final product. In FT-Raman spectra, the band centered at ∼ 500 cm–1 is due to Ni-O stretching (LO) mode, and two-magnon (2 M) scattering mode causes the band at 1514 cm–1. The synthesized product is composed of almost rod-shaped particles with a size range of 10–20 nm, according to FESEM pictures. The UV absorption studies showed a high absorption at the fundamental absorption edges originating at 332 nm, which gradually shifted to a lower energy region up to 400 nm with increasing precursor concentration, which means a reduction in bandgap values. The effect of precursor concentration associated with the electrical characteristics of the produced NiO nanoparticles has been investigated for the temperature range 30 to 130 °C. The I-V characterization was used to compute the different photo-diode parameters including n, ФB, Io, PS, R, QE, and D* . The remarkable high photosensitivity of 1100% and specific detectivity of 4.324 × 10−10 Jones for the diode evaluated at 120 mW/cm2 was observed in a 2 M fabricated diode. These findings imply that all the fabricated diodes are exceptionally light-sensitive and are well-suited for upcoming UV photodetector applications.

Nitrogen-doped carbon quantum dots decorated ZnO nanorods array film for efficient UV photodetector applications

Nitrogen-doped carbon quantum dots decorated ZnO nanorods array film for efficient UV photodetector applications

Tunable electronic and optical properties of Janus Al2M2ClBr (M = O, S) monolayers for UV photodetector applications

Janus Al2M2ClBr (M = O, S) monolayers were constructed to explore their potential for UV photodetector applications.

Preparation and Photovoltaic Performance of a Composite TiO2 Nanotube Array/Polyaniline UV Photodetector.

TiO2 has great potential for application in UV photodetectors due to its excellent photoelectric response. In this work, composite nanomaterials of TiO2 nanotube arrays (TiO2 NTAs) and polyaniline (PANI) were successfully prepared on titanium sheets using an anodic oxidation electrochemical method. The results showed that the TiO2 NTA/PANI composite materials had excellent UV photosensitivity and responsiveness and good stability and reproducibility. This was mainly attributed to the p-n heterostructure formed inside the TiO2 NTA/PANI composites that hindered the recombination of photogenerated electron-hole pairs and improved their utilization of UV light. This work provides a theoretical basis for the application of metal oxides in UV photodetectors, which is important for the development of UV photodetectors.

Photodetectors based on chemical vapor deposition or liquid processed multi-wall carbon nanotubes

Carbon nanotubes (CNTs) have attracted great interest for applications due to their unique mechanical, electronic and optoelectronic properties. The advantages of the multiple wall carbon nanotubes for optoelectronic devices like photodetectors and photodiodes are the large effective photo-collector surface as well as the possibility to tune the band gap and absorbance by controlling the growth parameters. In this work, we demonstrate two types of hybrid Multi-Wall CNTs/Si3N4/n-Si photodetectors based on ordered (produced with Chemical Vapor Deposition – CVD) and solution processed MWCNTs and evaluate their performance in UV and visual spectrum (275 nm, 655 nm). Device parameters were obtained by comparison of I–V characteristics to Schottky barrier models and C–V characteristics to standard MIS capacitor models. The role of silicon nitride layer was also examined by comparing devices with different nitride layer thickness. Focusing on the UV part of the spectrum, the solution processed device was photosensitive in the voltage range 3V–6V giving its best performance (External Quantum Efficiency - E.Q.E. 85%@275 nm) at 5V and illumination of 5 μW. The CVD processed device showed lower EQE for the same bias voltage range. Both devices showed a low performance in optical part of the spectrum compared to the corresponding one in the UV part of the spectrum. The mean optical responsivity values obtained at the UV part of the spectrum in both cases indicate that the Visible light blind MWCNT/Si3N4/n-Si system have a potential use in UV photodetector applications. In particular, solution processed devices may pave the way for cheap production of UV sensor systems.

Al2O3 barrier layer for enhancing UV to visible rejection ratio in p-Si/n-MgZnO heterojunction visible blind UV photodetectors

The fabrication of visible blind ultraviolet photodetectors based on p-Si/n-MgxZn1-xO heterojunction is challenging due to the generation of visible photoresponse caused by the drift of visible light generated electrons from p-silicon to n-MgxZn1-xO across the interface. Here, it is shown that by incorporating a thin ∼30 nm Al2O3 interlayer at the heterojunction, the UV-to-visible rejection ratio in p-Si/n-Mg0.25Zn0·75O photodetectors can be significantly enhanced. The Al2O3 interlayer inserted between n-Mg0.25Zn0·75O and p-Si serves as an effective blocking layer against the transport of visible light-generated electrons from p-Si to n-Mg0.25Zn0·75O, thereby suppressing the visible photoresponse. As a result, the UV-to-visible rejection ratio was improved by approximately three orders of magnitude, with a peak responsivity of 0.17 mA/W at 270 nm and a reverse bias of 0.5 V. This high degree of visible blindness of p-Si/n-Mg0.25Zn0·75O heterojunction photodetectors with an Al2O3 barrier layer holds promise for next-generation visible-blind UV photodetection applications.

Polarization-independent enhancement in UV photoconductivity of BiFeO3/Sn:In2O3 heterostructure

Currently, polarization-dependent transport in ferroelectric materials under optical illumination is gaining a lot of attention in optoelectronics. This idea is implemented on BiFeO3 to illustrate its UV–Visible light photodetection property, however, naturally occurring bismuth or oxygen vacancies serve a major disadvantage as they interfere with its polarization ability. It is very difficult to overcome this defect issue in bismuth-based perovskites, therefore, based on this herein an enhancement in the photoconductive property of polycrystalline BiFeO3 thin film deposited via spray pyrolysis technique on Sn:In2O3 coated glass substrate is demonstrated without polarizing it. An extraordinary photodetection behavior with higher photoresponsivity (1.01 A/W) and external quantum efficiency (364) as well as faster response speed (6 ms) even under low UV illumination (340 nm) and lower applied bias of 2 V is observed. The roles of the BiFeO3–Sn:In2O3 interface, as well as the adsorption/desorption of oxygen molecules on the surface of BiFeO3 layers, were highlighted for the ferroelectric material's UV photodetector application.

Cr-Doping-Induced Fano Resonance of ZnO-Layered Nanoporous Structures and UV Photodetector Application

Cr-Doping-Induced Fano Resonance of ZnO-Layered Nanoporous Structures and UV Photodetector Application

Transparent and flexible carbon dots/polymer scaffold for deep UV photodetection applications

Transparent and flexible carbon dots/polymer scaffold for deep UV photodetection applications

Investigation of Structural, Electronic, and Optical Properties of Chalcogen-Doped ZrS2: A DFT Analysis

The electrical and optical characteristics of a ZrS2 monolayer doped with chalcogen atoms (O, Se, or Te), where dopants are introduced by substituting the S atom, are examined on the basis of the density functional theory. The semiconductors pristine ZrS2 and O, Se, and Te-doped ZrS2 monolayers possessed indirect band gaps of 1.187 eV, 1.227 eV, 1.146 eV, and 0.922 eV, respectively. According to the formation energy, the O-doped ZrS2 monolayer is more stable compared to Se-doped and Te-doped ZrS2 monolayers. The optical properties are very similar for both the undoped and doped ZrS2 monolayers. The absorption coefficient and optical conductivity are the highest in the ultraviolet energy region. The designed materials are potentially suitable for UV photodetection and UV filtering applications.