High-performance UV Photodetectors Research Articles

High performance of UV photodetectors by integration of plasmonic Ag nanoparticles on GaN

High-performance ultraviolet photodetectors have attracted much attention due to their various potential applications from household to universal. On basis of this, in this work, a high – performance and photoresponse enhancement UV photodetector based on Ag NPs/GaN heterojunction was demonstrated. By incorporating of Ag nanoparticles, light confinement determined by Ag nanostructure offers an effective approach to break through the limitation of the light-mater interaction within the photoactive layers of photodetector. Various size and elemental composition of Ag NPs are fabricated on GaN lead to significant enhancement of photocurrent in UV photodetector. Consequently, an outstanding photoresponsivity of 89 A/W, external quantum efficiency of 2.8 × 103% at low bias voltage of 0.3 V were achieved. The improve photo-response of the Ag NPs-decorated GaN-based photodetector is attributed to the simultaneous effect of strong plasmon absorption, increased injection of hot electrons into the conduction band of GaN. This study will open up the direction to fabricate the high-performance UV photodetector.

High-performance Ga2O3 solar-blind UV photodetectors via film growth regulation and surface state engineering

Gallium oxide (Ga2O3) with a wide bandgap is emerging as one of the most promising candidates for solar-blind photodetectors (SBPDs). However, the practical application of Ga2O3-based SBPDs is impeded by substantial defects-related leakage currents, sluggish response speed, and high-cost, making their practical applications face great challenges. Here, we proposed strategic films growth regulation and surface state engineering to grow high-quality yet economical β-Ga2O3 films, thereby achieving high-performance SBPDs. High-resolution transmission electron microscopy revealed the presence of high-quality films with an extremely regular arrangement of β-Ga2O3 (2‾01) planes. The full width at half maximum and root mean square roughness values are 0.07° and 0.716 nm, respectively. The β-Ga2O3 films demonstrated a significant reduction in VO concentrations after O2/N2 plasma treatment. This process can effectively minimize thermal damage to the sample surface while retaining highly reactive free radicals. The photocurrents of devices can be further enhanced, leading to a larger PDCRs of 8.6 × 107, through N2 plasma treatment. Moreover, the films effectually suppress the persistent photoconductivity effect with τr and τd values of 5.31/0.97 s and 0.49/0.87 s before and after N2 plasma treatment, respectively. We have demonstrated the influence mechanism of O2/N2 plasma treatment on photoelectronic performance. This study provides a practical approach to growing high-quality β-Ga2O3 films and preparing high-performance but low-cost Ga2O3-based SBPDs.

High-performance and low-power consumption deep UV photodetectors based on MOCVD-grown ZnGa2O4epilayers with high temperature functionality

This work reports on the fabrication of excellent quality deep ultraviolet photodetectors (DUV PDs) based on metalorganic chemical vapor deposition (MOCVD) grown spinel ZnGa2O4 thin films on c-plane sapphire. Herein, The DUV PDs by exhibiting an ultra-low dark current of 6.69 fA and a high photo-to-dark-current ratio (PDCR) of >108 at a low-power operation of 0.2 V. While PDCR reached more than 109 on applied bias of 10 V having extremely low dark current of 37 fA. The detector revealed an ultra-high responsivity of 185 and 3.53 A/W under the exposure of 107 μW/cm2 of 245 nm wavelength at room temperature (RT) and applied bias of 10 and 0.2 V, respectively, and exhibited the record-high detectivity of the order of 1017 Jones. The temperature-dependent operation remained stable across a wide temperature range, from 27 °C to 125 °C, maintaining ultra-low dark current. The nearly constant growth and decay time of DUV PDs throughout the temperature range emphasizes the robustness and reliability of PD. The ideality factor in both DUV and dark conditions nearing unity proves the dominance of the thermionic emission mechanism. Also shows the stable and slight improved performance after a year. Therefore, these findings suggest that ZnGa2O4 is a strong contender for deep UV detection that shows robustness even at high temperatures.

High-performance self-powered UV photodetectors using SnO2 thin film by reactive magnetron sputtering

Self-powered UV photodetector (UVPD) operates without the need for an external energy source and contributes to global energy conservation. With ongoing innovation, self-powered PDs are becoming increasingly appealing for industrial and innovation applications such as advanced environmental monitoring and communication devices. This study investigates the influence of varying working pressures (ranging from 3 to 15 mTorr) during reactive magnetron sputtering on the crystalline structure, surface morphology, and performance of SnO2 thin film photodetectors, aiming to fabricate self-powered UVPDs. The SnO2-based UVPD demonstrates exceptional self-powered UV photodetection capabilities, characterized by a sensitivity of 6.41×105%, responsivity of 0.09 mA/W, and detectivity of 2.99×1010 Jones. In addition, SnO2-based UVPD possesses a switching photo response and recovery time of 0.75 and 0.99 s. Henceforth, it was observed that 8 mTorr SnO2 thin film exhibits exceptional stability, superior photodetector performance, and remarkable repeatability, rendering them highly suitable for UVPD applications. Notably, these films demonstrate sustained functionality for approximately 100 days without necessitating encapsulation. These excellent results confirm that SnO2 thin films are suitable for fabricating future smart optoelectronics devices.

Plasmon-exciton interactions in ZnO/AuNPs heterostructure film for high photoconductivity

This study investigatesplasmon-exciton interactions within ZnO/AuNPs heterostructure films. Elemental, structural, and morphological analyses validate the successful formation of these films. The observed shift in the plasmonic resonance band and absorption edge otowards the red region the red region is attributed to strong surface plasmon damping influenced by exciton interactions within ZnO. Irradiation with blue light induces plasmonic electrons, generation in the ZnO/AuNPs film, enhancing electrical conductivity through interaction with ZnO excitonic states. UV light irradiating generates the electron-hole pair in the ZnO film and interacts with the free electrons in AuNPs. The ZnO/AuNPs heterostructure films hold promise for applications such as high-performance UV-photodetectors, photoactive layers in solar cells, light-emitting diodes, and energy storage devices.

Developing a high-performance UV photodetector by improving polyaniline polymer properties with multi-walled carbon nanotubes

Developing a high-performance UV photodetector by improving polyaniline polymer properties with multi-walled carbon nanotubes

Air-Stable Self-Driven UV Photodetectors on Controllable Lead-Free CsCu2I3 Microwire Arrays.

The rapid evolution of the Internet of Things has engendered increased requirements for low-cost, self-powered UV photodetectors. Herein, high-performance self-driven UV photodetectors are fabricated by designing asymmetric metal-semiconductor-metal structures on the high-quality large-area CsCu2I3 microwire arrays. The asymmetrical depletion region doubles the photocurrent and response speed compared to the symmetric structure device, leading to a high responsivity of 233 mA/W to 355 nm radiation. Notably, at 0 V bias, the asymmetric device produces an open-circuit voltage of 356 mV and drives to a short-circuit current of 372 pA; meanwhile, the switch ratio (Iph/Idark) reaches up to 103, indicating its excellent potential for detecting weak light. Furthermore, the device maintains stable responses throughout 10000 UV-light switch cycles, with negligible degradation even after 90-day storage in air. Our work establishes that CsCu2I3 is a good candidate for self-powered UV detection and thoroughly demonstrates its potential as a passive device.

Dual-coupling effect enables a high-performance self-powered UV photodetector.

Self-powered ultraviolet photodetectors generally operate by utilizing the built-in electric field within heterojunctions or Schottky junctions. However, the effectiveness of self-powered detection is severely limited by the weak built-in electric field. Hence, advances in modulating the built-in electric field within heterojunctions are crucial for performance breakthroughs. Here, we suggest a method to enhance the built-in electric field by taking advantage of the dual-coupling effect between heterojunction and the self-polarization field of ferroelectrics. Under zero bias, the fabricated AgNWs/TiO2/PZT/GaN device achieves a responsivity of 184.31 mA/W and a specific detectivity of 1.7 × 1013 Jones, with an on/off ratio of 8.2 × 106 and rise/decay times reaching 0.16 ms/0.98 ms, respectively. The outstanding properties are primarily attributed to the substantial self-polarization of PZT induced by the p-GaN and the subsequent enhancement of the built-in electric field of the TiO2/PZT heterojunction. Under UV illumination, the dual coupling of the enhanced heterojunction and the self-polarizing field synergistically boost the photo-generated carrier separation and transport, leading to breakthroughs in ferroelectric-based self-powered photodetectors.

Sol-Gel Synthesized Amorphous (InxGa1−x)2O3 for UV Photodetection with High Responsivity

β-Ga2O3 photodetectors have the advantages of low dark current and strong radiation resistance in UV detection. However, the limited photocurrent has restricted their applications. Herein, MSM UV photodetectors based on (InxGa1−x)2O3 (x = 0, 0.1, 0.2, 0.3) by a sol-gel method were fabricated and studied. The doping of indium ions in Ga2O3 leads to lattice distortion and promotes the formation of oxygen vacancies. The oxygen vacancies in (InxGa1−x)2O3 can be modulated by various proportions of indium, and the increased oxygen vacancies contribute to the enhancement of electron concentration. The results show that the amorphous In0.4Ga1.6O3 photodetector exhibited improved performances, including a high light-to-dark current ratio (2.8 × 103) and high responsivity (739.2 A/W). This work provides a promising semiconductor material In0.4Ga1.6O3 for high-performance MSM UV photodetectors.

High-performance UV photodetector based on nickel oxide loaded with low amount of nitrogen and boron co-doped reduced graphene oxide for bias-switchable photoconductance

In this work, we report a low cost and straightforward chemical synthesis of nickel oxide nanoparticles decorated with low amount of nitrogen and boron co-doped reduced GO for a high-performance UV photodetector. For the first time, NiO/NB-rGO nanomaterial was synthesized following the co-precipitation method and subsequently annealed at 400 °C. The nanomaterial was characterized with several techniques such as SEM, TEM, XRD, and Raman spectroscopy. In addition, the device was subjected to electrical characterizations to determine their responsivity, detectivity, and temporal responses both in the absence of illumination (dark conditions) and under UV illumination of 375 nm. In particular, the studied I-V curve was performed to evaluate the coexistence of positive and negative photoconductivity in our device. The results revealed a better photoresponse of NiO/NB-rGO device to UV light, which showed high responsivity (800 A/W), large detectivity (9.4 ×1011 Jones), and fast rise/fall time (1.38/2.17 s) at reverse bias. Consequently, the Schottky contact of NiO/NB-rGO allowed to switch between carriers’ conduction, which displayed both positive and negative photoconductance at reverse and forward bias.

Interface modification of MoS2/ZnO heterojunction for controllable electron flow and fabrication of high-performance UV photodetectors with fast response/recovery speed

Hetero-structured thin films, MoS2/ZnO thin films, were fabricated by adding MoS2 films under the ZnO thin films via sol-gel spin-coating method; ZnO nanoparticles were observed on the surface of sol-gel spin-coated ZnO thin films. Although ZnO nanoparticles were observed on the surface of hetero-structured thin films, the surface area of the hetero-structured thin films was higher than ZnO thin films owing to the high surface roughness of the MoS2 films. Three diffraction peaks were observed in the hetero-structured thin films at 31.74°, 34.38°, and 36.22°, which indicates heterostructure was polycrystalline, and the heterostructure was formed successfully. When the UV photodetector was fabricated by using hetero-structured thin films, the enhanced values of photocurrent, photoresponsivity and photosensitivity were observed. In addition, the hetero-structured thin films exhibited a faster response/recovery speed because the move of electrons and holes during UV illumination. Thus, it was concluded that the interface modification of the MoS2/ZnO heterojunction is an effective solution for overcoming the drawbacks of ZnO-based UV photodetectors. This approach can be considered a novel method for high-performance optoelectronics with fast response speed applicable to various fields.

An efficient MSM UV photodetector with an ultra-low dark current enhanced by a back to back TiO2/PbTiO3 PN heterojunction

A TiO2 MSM UV photodetector has been extensively researched and exhibits many good properties such as stability and a large ratio of light to dark current. However, it suffers from a high dark current and slow response and recovery. In this work, an MSM UV photodetector based on a TiO2/PbTiO3 heterojunction was fabricated by a sol-gel method. Spontaneous polarization of ferroelectric perovskite PbTiO3 can deplete carriers and accelerate the separation and transport of photo-generated carriers. The photodetector showed enhanced performances, including an ultra-low dark current (1.146 19 × 10−11 A), an improving ratio of light to dark current, as well as short response and recovery times (decreasing to 65 and 81 ms). These results indicate the potential in the combination of ferroelectric perovskite PbTiO3 with traditional wide bandgap semiconductor materials to fabricate high-performance UV photodetectors.

Two-dimensional perovskite NdNb2O7 for high-performance UV photodetectors by a general exfoliation and assembly strategy

Two-dimensional (2D) oxide perovskites show great promise as candidates for future optoelectronic devices. For the first time, we have successfully exfoliated 2D perovskite NdNb2O7 (NNO) nanosheets by a solid-state calcination and liquid-phase exfoliation method. The individual NNO nanosheet photodetector (PD) demonstrates outstanding performance in detecting UV light (260 nm, 3 V), including high responsivity (62 AW−1), high detectivity (6.7 *1012 Jones), high spectral selectivity (R260/R400= 9000), fast response speed (0.1/7.8 ms) and long-term stability. Furthermore, through a simple interface self-assembly technique, we have successfully achieved orderly and flat films of NNO nanosheets. The resulting film exhibits high transparency (>75 %) in the visible light range. The NNO film device demonstrates excellent performance after undergoing numerous bending tests. This work not only presents a new candidate for high-performance and high-stability UV photodetectors but also introduces a general exfoliation and assembly strategy.

Semiconductor applications of Yb2O3: Constructing heterojunction solar-blind UV photodetectors with graphene

Exploring the semiconductor materials with suitable gap and chemical stability is the key to developing solar-blind ultraviolet photodetectors with high stability, responsivity, and detectivity. However, available materials are limited currently, hindering the development of solar-blind detectors greatly. Rare earth oxides (Yb2O3) have the bandgap and high-dielectric constants suitable for solar-blind detection, but its potential of being applied to broadband gap semiconductors has not been deeply studied. Therefore, to activate the semiconductor characteristics of Yb2O3, this work builds a p-Gr/i-Yb2O3/n-Si heterojunction solar-blind ultraviolet photodetector by introducing single-layer graphene. Through tests, this device has an absorption cutoff wavelength of 271 nm, which can almost cover the entire solar-blind ultraviolet band, and a high responsivity of 9.78 mA/W under 0 V bias with the rise and fall time as short as 87 and 73 ms, respectively. This work not only prepares a high-performance solar-blind UV photodetector but also presents the potential application of Yb2O3 in the solar-blind ultraviolet light detection. The high-dielectric performance of rare earth oxides makes it expected to be used for the photoelectric chip unit in future integrated circuit.

High-performance UV light detector using layered perovskites and textured silicon heterojunction

UV photodetectors have gained popularity due to their high precision and capability to filter out interference from solar electromagnetic radiation. A UV detector of (BA)2PbCl4/textured silicon (BA = n-butylammonium) heterojunction was fabricated by depositing (BA)2PbCl4 thin film on textured silicon. High performances of a rapid UV light response (trise = tfall = 0.24 s), high responsivity (8.16 mA/W), and a low detection limit (7.5 μW/cm2) were obtained from the designed detector, which were ascribed the unique morphology and structure of the detector. The rough surface morphology of textured silicon enlarges the light-absorbing area of (BA)2PbCl4 by 20 times. Moreover, a p-n junction was constructed between (BA)2PbCl4 and textured silicon. The electric field naturally present in the heterojunction facilitates the transport of carriers. Furthermore, the (BA)2PbCl4/textured silicon heterojunction exhibited significant selectivity towards UV light and demonstrated remarkable stability and repeatability in the air environment. This work offers a new strategy for developing inexpensive and high-performance UV photodetectors, which is significant for exploring the potential of layered perovskites in new photodetector device applications.

Effect of oxygen pressure during the growth of ZnSnO3 epitaxial thin films on LiNbO3 substrates

High-quality ZnSnO3 epitaxial films are grown on LiNbO3(0001) substrates by pulsed laser deposition in an oxygen pressure range of 0.1–10 Pa. The crystalline quality, composition, surface topography, structure, defect formation energy and photovoltaic properties of the epitaxial films are found to be highly sensitive to change in the oxygen pressure by experiments and first-principles density functional theory (DFT). The epitaxial relationship between the film and the substrate is identified as ZnSnO3(0001) || LiNbO3(0001) with ZnSnO3 [2¯ 110] || LiNbO3[2¯ 110]. The film grown atPO2 = 10 Pa has the highest crystal quality, but the photodetector based on the film obtained atPO2 = 0.1 Pa presents the highest responsivity (2.24 A/W at 1 V) and light/dark current ratio (∼105 at 1 V) under the 254-nm-light irradiation. Our results indicate that the as-grown ZnSnO3 epitaxial film should be a potential material for fabricating high-performance UV photodetectors.

Two-In-One: End-Emitting Blue LED and Self-Powered UV Photodetector based on Single Trapezoidal PIN GaN Microwire for Ambient Light UV Monitoring and Feedback.

With the continuous miniaturization and integration of the semiconductor industry, micro/nanoscale integrated photonics has received extensive attention as a key technology for optical communication, optical storage, and optical interconnection. Here, a two-in-one device is reported with both unidirectional blue light emission and UV photodetection functions based on single trapezoidal PIN GaN microwire. By constructing a Fabry-Perot resonator cavity structure, the end-emitting blue light-emitting diode with a low turn-on voltage (≈0.97V) and high color purity (full width at half maximum ≈22nm) is implemented. Furthermore, benefiting from the slow growth rate of the semipolar planes on both sides of the trapezoidal microwire and the high diffuse reflectivity of the patterned substrate, the trapezoidal microwire sides can be used as a high-performance UV photodetector. In self-driven mode, the device exhibits a large responsivity (0.218AW-1 ), high external quantum efficiency (83.31%) and fast response speed (rise/decay time of 0.48/0.98ms). Finally, the prepared two-in-one device is successfully integrated into ambient light UV monitoring and feedback system and tested. This work provides a novel strategy to combine luminescence with photodetection, demonstrating high potential for applications, such as on-chip photonic integration, energy-saving communication and ambient light monitoring and feedback system.

High-Performance Nanoplasmonic Enhanced Indium Oxide—UV Photodetectors

In this paper, high-performance UV photodetectors have been demonstrated based on indium oxide (In2O3) thin films of approximately 1.5–2 μm thick, synthesized by a simple and quick plasma sputtering deposition approach. After the deposition, the thin-film surface was treated with 4–5 nm-sized platinum (Pt) nanoparticles. Then, titanium metal electrodes were deposited onto the sample surface to form a metal–semiconductor–metal (MSM) photodetector of 50 mm2 in size. Raman scattering spectroscopy and scanning electron microscope (SEM) were used to study the crystal structure of the synthesized In2O3 film. The nanoplasmonic enhanced In2O3-based UV photodetectors were characterized by various UV wavelengths at different radiation intensities and temperatures. A high responsivity of up to 18 A/W was obtained at 300 nm wavelength when operating at 180 °C. In addition, the fabricated prototypes show a thermally stable baseline and excellent repeatability to a wide range of UV lights with low illumination intensity when operating at such a high temperature.

Thermionic Emission of Atomic Layer Deposited MoO3/Si UV Photodetectors.

Ultrathin MoO3 semiconductor nanostructures have garnered significant interest as a promising nanomaterial for transparent nano- and optoelectronics, owing to their exceptional reactivity. Due to the shortage of knowledge about the electronic and optoelectronic properties of MoO3/n-Si via an ALD system of few nanometers, we utilized the preparation of an ultrathin MoO3 film at temperatures of 100, 150, 200, and 250 °C. The effect of the depositing temperatures on using bis(tbutylimido)bis(dimethylamino)molybdenum (VI) as a molybdenum source for highly stable UV photodetectors were reported. The ON-OFF and the photodetector dynamic behaviors of these samples under different applied voltages of 0, 0.5, 1, 2, 3, 4, and 5 V were collected. This study shows that the ultrasmooth and homogenous films of less than a 0.30 nm roughness deposited at 200 °C were used efficiently for high-performance UV photodetector behaviors with a high sheet carrier concentration of 7.6 × 1010 cm-2 and external quantum efficiency of 1.72 × 1011. The electronic parameters were analyzed based on thermionic emission theory, where Cheung and Nord's methods were utilized to determine the photodetector electronic parameters, such as the ideality factor (n), barrier height (Φ0), and series resistance (Rs). The n-factor values were higher in the low voltage region of the I-V diagram, potentially due to series resistance causing a voltage drop across the interfacial thin film and charge accumulation at the interface states between the MoO3 and Si surfaces.

A high-performance UV photodetector with superior responsivity enabled by a synergistic photo/thermal enhancement of localized surface plasmon resonance

We report the development of a high-performance UV photodetector based on W18O49/TiO2 nanofibers enabled by plasmon-induced synergistic photo/thermal enhancement; the responsivity of this device significantly exceeds those of TiO2-based photodetectors reported to date.