Heterojunction Ultraviolet Photodetector Research Articles

Ultrasensitive self-powered broadband ultraviolet photodetectors based on n-(Ga0.9Sn0.1)2O3/n-TiO2 heterojunction

Ga2O3-based self-powered ultraviolet (UV) photodetectors (PDs) have recently attracted much interest, but they need to be fabricated via complex and expensive vacuum equipments, and the photoresponse performances are not quite good. To solve these problems, we have developed high-property (Ga0.9Sn0.1)2O3/TiO2 heterojunction UV PDs by a low-cost, effective, and facile sol-gel way. Sn4+ possesses higher valence in comparison with Ga3+, and Sn-O bonding energy is weaker than Ga-O bonding energy, which are both in favor of increasing electron concentrations of n-type Ga2O3, resulting in improved photocurrent. TiO2 can form type-II band alignment when it contacts with (Ga0.9Sn0.1)2O3, which is beneficial for separating and transporting photo-generated carriers of the heterojunction PDs. Consequently, a high responsivity of 57.86mA/W, large detectivity of 9.33×1011 Jones, and quick response rate with a rise/decay time of 0.05/0.66s at a light wavelength of 230nm and 0V bias are achieved in the Au/(Ga0.9Sn0.1)2O3/TiO2/FTO heterojunction PDs. More encouragingly, because the (Ga0.9Sn0.1)2O3 and TiO2 possess strong absorption characteristics for UVC, and UVB and UVA light, respectively, the heterojunction self-powered PDs present superior broadband detection capacity across ultraviolet A to ultraviolet C spectrum.

Solid–liquid heterojunction UV photoelectrochemical photodetector based on WO3 nanosheets and acidic electrolyte

The acid-resistant tungsten trioxide photoelectrochemical solid–liquid ultraviolet (UV) photodetector uses a thin film of tungsten trioxide as the photoelectrode, forming a stable heterojunction with the electrolyte. This study employed band theory and double electron layer theory to analyze the mechanisms underlying the effect of pH on the redox potential and photocurrent, utilizing the ion product constant of water and the Nernst equation. By applying the principles of energy band theory and the two-electron layer model, the electron transfer process was analyzed and explained. These findings hold significant promise for enhancing solid–liquid heterojunction UV photodetectors. Tungsten trioxide has fast response and high sensitivity under extreme conditions. The device performance of WO3 nanosheets fabricated by annealing at 300 °C for one hour is excellent, including a rise time of 0.7 s, decay time of 6.8 s, photosensitivity of 1.90, and photoresponsivity of 2.31 mA/W. 0.5M sulfuric acid produced the highest photocurrent (5.46 μA) and sensitivity (14.07). This material has potential applications in optoelectronics, catalysis, sensing, water treatment, and air purification.

Self-powered poly(3-hexylthiophene)/ZnO heterojunction ultraviolet photodetectors decorated by silver nanoparticles

Self-powered poly (3-hexylthiophene)/zinc oxide (P3HT/ZnO) heterojunction ultraviolet photodetectors decorated by silver nanoparticles (Ag NPs) were fabricated by sol-gel and spin-coating techniques. The ultraviolet photoresponse performance of the P3HT/ZnO heterojunction photodetectors influenced by the position of plasmonic Ag NPs was investigated. The responsivity and detectivity of the P3HT/Ag/ZnO photodetector with placed Ag NPs at the interface of ZnO and P3HT layers enhanced to 1.92 and 1.15 times compared to the reference devices. When the Ag NPs embedded into ZnO layer, the responsivity, detectivity and external quantum efficiency were 16.42 mA/W, 5.97 × 1011 Jones, and 5.36 %, respectively, which were 5.77 times, 4.64 times and 5.77 times to that of the pristine P3HT/ZnO photodetector. The enhancement mechanism of plasmonic metallic nanoparticles to the performance of the photodetectors was discussed in details. This study presents a simple route to high performance self-powered photodetectors.

Multi-effect coupling enhanced self-powered heterojunction ultraviolet photodetector with ultra-low detection limit

Convenient, small-sized, and self-powered sensor units are easier to integrate, making them the future development direction of photodetectors. GaN materials with wide band gap are powerful candidates for UV detection, but most GaN based self-powered UV photodetectors have poor detection ability for the weak UV light, which limits their applications. This study reports a self-powered UV photodetector based on BaTiO3/GaN heterojunction, which can detect ultra-weak UV light at a minimum of 0.68 nW/cm2 by coupling the ferroelectric polarization, anti-reflection effect, and pyro-phototronic effect. The polarized BaTiO3 thin film on the surface of GaN has an enhanced residual polarization field and generated anti-reflection effect, which can regulate the heterojunction band structure, suppress the dark current and minimize surface reflection of GaN. Simultaneously enhanced pyro-phototronic effect can significantly improve the response speed and responsivity of the device. The response time and recovery time of the device are as low as 8.794 ms and 5.018 ms. The maximum responsivity and detectivity are 88.206 mA/W and 7.392 × 1013 Jones, respectively, increased by 359% and 6065% compared to the device before polarization. Thanks to excellent material stability, the device has a sensitive and uniform response to continuously incident UV light. In addition, by simulating flame generation, it has been proven that the device has brilliant performance in flame detection and can achieve remote monitoring and fire warning functions. These results can promote the potential application of self-powered UV photodetectors based on BaTiO3/GaN heterojunction in environmental monitoring and space communication fields.

Integrating interface engineering and plasmonic effect to boost photoresponse performance of ZnO:Ga/GaN heterojunction self-powered UV photodetectors

The ability to function without an external power supply makes photodetectors highly promising for use in a new generation of wirelessly and independently operated ultraviolet (UV) photodetection and imaging systems. However, self-powered photodetectors' high dark current, inadequate light harvesting, and poor carrier separation prevent them from attaining high-efficiency UV photodetection and imaging. Herein, a high-performance heterojunction UV photodetector consisting of a single Ga-doped ZnO microwire enshrouded by Ag nanowires (AgNWs@ZnO:Ga MW), a MgO electron blocking layer, and a p-type GaN wafer was proposed. Taking full advantage of the interface engineering and plasmonic effects, the AgNWs@ZnO:Ga MW/MgO/GaN photodetector achieves high photodetection performance with an excellent responsivity of 262 mA/W, a remarkable external quantum efficiency of 92.37%, and a high detectivity of 1.966 × 1012 Jones under 370 nm illumination with power density of 0.22 mW/cm2. Furthermore, it also demonstrates ultrafast pulsed photoresponse speed with a rise/fall time of 3.64 μs/252 μs. An UV imaging system is designed based on the AgNWs@ZnO:Ga MW/MgO/GaN self-powered photodetector, allowing for high-quality, accurate, and distinct object imaging. This work combines interface engineering and plasmonic effects for achieving high-performance UV photodetection, which provides a strategic approach to the development of highly efficient optoelectronic devices.

Power-free, filter-free and high-performance narrowband ZnO/BaTiO3/GaN heterojunction ultraviolet photodetector induced by synergetic plasmonic and ferroelectric effects

Narrowband ultraviolet photodetectors play a critical role in missile detection, flame monitoring, communication and other fields. Most commercial narrowband photodetectors, which are currently obtained by combining bandpass filters, face challenges...

High storage and operational stability self-powered UV photodetector based on p-CuI/n-GaN heterojunction prepared by thermal evaporation method

Self-powered ultraviolet (UV) photodetectors play an important role in environmental monitoring, aerospace and other fields because of the advantage of effective light response without an external power supply. Herein, a p-CuI/n-GaN heterojunction UV photodetector with self-powered function is constructed by vacuum thermal evaporation method. At 365 nm UV irradiation, the photodetector has an on/off ratio of 7536, a large photocurrent (∼35 mA) and a fast response time (rise/decay time of 10.46/10.35 ms) at zero bias. There was no significant decrease in photocurrent during the 100 on/off cycles of the continuous test, and the photocurrent of the photodetector can maintain 93.17% of the initial value after continuous operation for 15 h without bias voltage. The rise in ambient temperature exhibits a negative effect on the UV photodetector, but when it is naturally cooled from 80℃ to room temperature (RT), the photocurrent can restore to 95% of the original level. Furthermore, the photodetector maintains superior stability even after being stored in air for 3 months of without package. This work not only proves the controllable preparation strategy of CuI thin films, but also provides an efficient structure for self-powered UV photodetectors with high operational and storage stability.

Improved detection performance of self-driven InZnO / p-GaN heterojunction UV photodetector by lanthanum doping

By using the sol-gel spin-coating method, La-InZnO films with different La (0 at%, 2 at%, 4 at%, and 6 at%) doping concentrations were grown on p-GaN / sapphire film templates, and self-driven p-GaN / n-ZnO heterojunction ultraviolet (UV) detectors were prepared. The effects of La doping concentration on the microstructure, optical, and electrical properties of synthesized La-InZnO films were studied. In addition, the optical sensing characteristics and photoelectric response performance of four p-n heterojunction UV detectors were compared. La doping can decrease the content of oxygen vacancies. It also reduces the carrier concentration and mobility of the films. At zero bias voltage, the 2 at% doped device has the best performance, with a peak responsivity of 46 mA/W at 366 nm, a high spectral selectivity full width at half maximum (FWHM) of only 6.92 nm, and a fast response with the rise and decay times of 1.15 ms and 2.42 ms, respectively. This study demonstrates a feasible method for improving the performance of self-driven heterojunction UV detectors.

Pyro-Photoelectric Effect Enhanced Dual-Mode Self-Powered ITO/ZnO:Ga Microwire/AlGaN Thin-Film Heterojuncted Ultraviolet Imaging Photodetector

Ultraviolet (UV) photodetectors have received a significant amount of attention in a variety of areas; especially, self-powered photodetectors are anticipated to address the energy-saving demand in the astronautics under the photovoltaic effect. In this work, a ZnO:Ga/Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.9</sub> N heterojunction is introduced for performing UV photodetector, which is enhanced by the pyro-photoelectric effect coupling of pyroelectric and photovoltaic effects. The heterojunction UV photodetector can operate in a self-powered mode with responsivity of 0.063 mA W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> under the illumination of 135 μW cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . More importantly, after pyro-photoelectric enhancement, the photocurrent is effectively increased from 13 pA to 45 pA. Additionally, under the illumination of 493 μW cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , the photo-to-dark-current ratio ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PDCR</i> ) of 80 and 1.7 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> are obtained at reverse bias of -10 V and forward bias of +10 V, respectively, indicating that the heterojunction UV photodetector can be regarded as a dual-mode photodetector since it can operate in both forward-biased photoconductive mode and reverse-biased depletion mode. Moreover, the UV photodetector exhibits a fast temporal pulsed laser response with a rising time of 0.79 ms and decay time of 9.4 ms. In all, this work presents a novel strategy for the advancement of UV detection.

A self-powered ultraviolet photodetector based on TiO2 nanoarrays and poly(3,4-ethylenedioxyselenophene) with the enhanced performance by pyro-phototronic effect

Pyro-phototronic effect plays an important role in improving the photodetection performance of ultraviolet (UV) photodetectors (PDs). Here, a novel pyro-phototronic effect between TiO2 nanoarrays (TiO2 NRs) and the conducting polymer poly(3,4-ethylenedioxy selenophene) (PEDOS) is applied to fabricate a self-powered UV PD with the enhanced photodetection ability. The self-powered p-n heterojunction UV PD is fabricated by a face-to-face hybrid of acid (HCl and H2SO4)-treated TiO2 NRs with PEDOS. Interestingly, a pyro-phototronic effect is found between TiO2 NRs/FTO and PEDOS/FTO, and the acid treatment of TiO2 NRs can dramatically enhance the pyro-phototronic effect. H2SO4 treatment can improve the p-n heterojunction, while HCl treatment can increase carrier concentration due to the introduction of surface oxygen vacancies on the surface of TiO2 NRs. Under UV light illumination and 0 bias voltage, the rise time (Trise) and fall time (Tfall) of UV PD from the face-to-face hybrid of PEDOS/FTO with TiO2(HCl)/FTO are 0.080 s and 0.079 s, while the responsivity (R) and detectivity (D*) are 58.706 mA/W and 3.627 × 1011 Jones, respectively. The face-to-face fabrication of UV PDs and the matching of the energy levels between PEDOS and TiO2 NRs cause the pyro-phototronic effect due to temperature change and pyroelectric effect of TiO2 NRs under the UV light illumination. This work gives a new idea to generate pyro-phototronic effect between TiO2 NRs and conducting polymers for application in UV PDs field.

Ultrafast response self-powered UV photodetectors based on GaS/GaN heterojunctions

Self-powered ultraviolet (UV) photodetectors (PDs) based on GaN have been of great importance in the application of UV communication, thanks to its wide direct bandgap and strong resistance to irradiation. However, current self-powered GaN-based heterojunction UV photodetectors could not meet the requirement of fast photoresponse. Herein, type-II pn heterojunction GaS/GaN-based self-powered PDs have been proposed with a naturally p-type doping GaS thin film grown on n-type GaN via chemical vapor deposition. The electronic and optical properties of GaS/GaN heterojunction were investigated via experiments and the density functional theory. Afterward, as-prepared GaS/GaN-based PDs reveal an excellent self-powered photosensitivity/detectivity of 6.26 mA W−1/8.29 × 109 Jones at 0 V at 365 nm, ultrafast response speed with a rise/fall time of 48/80 μs as well as an amazing rejection ratio (R365 nm/R500 nm) of 3.42 × 104, and a fine rectification ratio of 105.9. This work provides a feasible method to synthesize high-performance GaS/GaN heterojunctions and demonstrates their enormous potential in ultrafast response self-powered UV photodetection.

High-Performance NiO/TiO2/ZnO Photovoltaic UV Detector

The ultraviolet (UV) photodetector has found many applications, ranging from optical communication to environmental monitoring. There has been much research interest in the development of metal oxide-based UV photodetectors. In this work, a nano-interlayer was introduced in a metal oxide-based heterojunction UV photodetector to enhance the rectification characteristics and therefore the device performance. The device, which consists of nickel oxide (NiO) and zinc oxide (ZnO) sandwiching an ultrathin dielectric layer of titanium dioxide (TiO2), was prepared by radio frequency magnetron sputtering (RFMS). After annealing, the NiO/TiO2/ZnO UV photodetector exhibited a rectification ratio of 104 under UV irradiation of 365 nm at zero bias. The device also demonstrated a high responsivity of 291 A/W and a detectivity of 6.9 × 1011 Jones at +2 V bias. Such a device structure provides a promising future for metal oxide-based heterojunction UV photodetectors in a wide range of applications.

Ultrasensitive self-powered heterojunction ultraviolet photodetector of p-GaN nanowires on Si by halide chemical vapour deposition

In this study, we report the fabrication of quasi-aligned p-GaN nanowires (NWs) on n-Si (1 1 1) substrate by halide chemical vapour deposition (HCVD) using MgCl2 precursor and followed by low-energy electron beam irradiation to activate the Mg acceptor doping in GaN NWs. We aimed to attain a comprehensive understanding of p-doping in GaN NWs growth, extensive characterizations and fabrication of UV photodetector (PDs) based on p-GaN NWs/n-Si heterojunction. To realize the efficient UV photodetectors, we measure the current–voltage (I–V) characteristics of heterojunction PDs under dark and illuminated conditions and the I–V curve demonstrates good rectifying behaviours with 0.2 V turn-on voltage. At zero bias, the heterojunction PDs show a reverse photocurrent of 1.27 × 10−6 A with a very low dark current of 2.35 × 10−9 A under 325 nm UV illumination. Besides, the significance of the self-powered operation of UV PDs and the charge transfer mechanism are discussed with the aid of the energy band diagram. The substantial photocurrent increment with varying applied potential leads to narrowing the photo potential in the interface. The excitonic bound states present in p-GaN NWs/n-Si heterojunction is further elucidated. As a result, the heterojunction PDs demonstrate the high responsivity, detectivity, and external quantum efficiency of 134 mA W−1, 3.73 × 1013 Jones, and 51% respectively, at 0.1 V low applied potential under the reverse bias condition. The proposed work provides an archetype for Mg doping in GaN NWs ensembles, which will help to facilitate the heterojunction with n-Si to unleash the potential of self-powered UV PDs.

Photoresponse of solution-processed transparent heterojunction ultraviolet photodetectors composed of n-type ZTO and p-type NiO-based semiconductor thin films

The n-type zinc-tin oxide (ZTO) and p-type nickel oxide (NiO) semiconductor thin films were prepared by the sol-gel spin coating process. The influence of 4 at% Mg and Cu doping on the microstructural, optical, and electrical characteristics of NiO thin films and physical properties of ZTO thin film were investigated. In addition, bi-layered ZTO/NiO thin films were grown onto Corning glasses to develop a visible light transparent p-n heterojunction ultraviolet (UV) photodetector. Mg doping slightly enhances the visible transparency and enlarges the optical bandgap energy, while Cu doping decreases the visible transparency and narrows the optical bandgap energy. The electrical properties of NiO sol-gel thin films were improved through Mg and Cu doping. According to the current-voltage (I–V) characteristic curves, the n-ZTO/p-NiO:Mg photodetector had the highest rectification ratio of 11.7 and on-to-off current ratio of 18.3 at 5 V bias. Under UV illumination, the three kinds of devices all exhibited a self-powered nature, while the Mg- and Cu-doped NiO devices had better photoresponse characteristics than the undoped NiO device. It was found that the Mg-doped NiO devices displayed the best photoconductivity gain and sensitivity, and acceptable response speed and responsivity, with applied reverse bias of 1 V.

Fowler-Nordheim tunneling mechanism for performance improvement in graphene 2D/GaN 3D heterojunction ultraviolet photodetector

The Fowler-Nordheim tunneling (FNT) is an important tunneling mechanism and an efficient route to improve the photoresponse of a photodetector. Herein, we report the quantum mechanical FNT mechanism based on graphene 2D/GaN 3D ultra-shallow van der Waals heterojunctions ultraviolet (UV) photodetector via atomic layer deposition Al2O3 tunneling layer, and the conversion between direct tunneling (DT) and FNT has also been systematically studied. At reverse bias (<−0.253 V) with the high build-in field, the high-speed photogenerated carriers overcome the thin insulator layer through the FNT, occurring impact ionization during the process resulting in a multiplication of the photocurrent. Consequently, the photodetector demonstrates pronounced photoresponse performances working under a weak light of 5 μW/cm2 at −2 V, including remarkable responsivity (122.57 A/W), ultrahigh specific detectivity (5.63 × 1014 Jones), and high sensitivity (1.29 × 107%), which indicated that the device has excellent weak light detection ability. This work presents a novel route to fabricate high-performance optoelectronic devices by using the FNT tunneling mechanism.

(Invited) III-Oxide/III-Nitride Heterostructures for Power Electronics and Optoelectronics Applications

Due to their large bandgap, high critical electric field, and availability of high-quality large-size melt-grown bulk substrates, III-oxides including Ga2O3, Al2O3, In2O3, and their alloys have been extensively investigated for a myriad of electronic and optoelectronic applications. Recently, β-Ga2O3 based power electronics, RF transistors, and ultraviolet (UV) photodetectors have been demonstrated with promising performance. However, p-type β-Ga2O3 is still elusive due to high dopant activation energy (>1 eV), large hole effective mass, and hole trapping. This significantly limits the design freedom for β-Ga2O3 devices. Other p-type semiconductors have been proposed to form heterostructures with β-Ga2O3 such as p-NiO, p-Cu2O, and p-type III-nitrides. As popular wide bandgap semiconductors, III-nitrides are promising candidates to form III-oxide/III-nitride heterostructures to enable advanced device structures and new functionalities. Furthermore, III-oxides and III-nitrides can be epitaxially grown on each other with small lattice mismatch (< 5% for GaN and β-Ga2O3) by the industrial standard epitaxial method MOCVD. For example, vertical GaN violet LEDs grown on n-type β-Ga2O3 substrates have been reported. This talk will present our recent work on III-oxide/III-nitride heterostructures in power electronics and optoelectronics.For power electronics, β-Ga2O3/GaN p-n heterojunctions will first be discussed. The heterojunction via mechanical exfoliation shows decent forward rectifying behaviors and thermal stability up to 200 °C but relatively low breakdown voltages (BV). To improve the breakdown capability, we carried out a comprehensive TCAD simulation study to design mesa edge termination for kV-class β-Ga2O3/GaN p-n heterojunctions. It was found that the electric field crowding effect is the main reason for the low BV. Several mesa edge termination structures were investigated such as deeply-etched mesa, step mesa, and p-GaN guard ring. Second, normally-off AlN/β-Ga2O3 field-effect transistors using polarization-induced doping will be discussed. A large two-dimensional electron gas is formed at the AlN/β-Ga2O3 interface due to polarization effects, and p-GaN gate is used to realize tunable positive threshold voltage. The device transfer and output characteristics with different device structures are also studied. For optoelectronics applications, self-powered spectrally distinctive Ga2O3/GaN heterojunction UV photodetectors grown by MOCVD will be discussed. Opposite current polarities are observed under different illumination wavelengths due to different carrier transports, which can be utilized to distinguish different spectra. These results indicate that (ultra)wide bandgap III-oxide/III-nitride heterostructures are a promising platform to enable new device structures and functionalities.

Self-powered photodetector based on poly(3-hexylthiophene) / Zinc oxide quantum dots Organic-inorganic hybrid heterojunction

The ZnO quantum dots (QDs) was synthesized by the sol–gel method and spin-coated into films to prepare n-ZnO/p-poly(3-hexylthiophene) hybrid heterojunction ultraviolet photodetectors (PDs) with different film thicknesses. Under optimal critical film thickness, 0 bias voltage and ultraviolet light (360 nm) irradiation, the device yields a photo-dark current ratio of ∼ 990, the quantum efficiency of ∼ 1.05 %, the highest photoresponsivity of ∼ 3.04 mA/W, detectivity of ∼ 1010 Jones and fast rise/fall time of ∼ 23 ms. This work paves the way for the development of low-cost and high-performance PDs.

Ultraviolet Photodetector Based on Poly(3,4-Ethylenedioxyselenophene)/ZnO Core–Shell Nanorods p-n Heterojunction

In this work, we successfully assembled an organic–inorganic core–shell hybrid p-n heterojunction ultraviolet photodetector by the electropolymerization deposition of poly(3,4-ethylenedioxyselenophene) (PEDOS) on the surface of zinc oxide nanoarrays (ZnO NRs). The structures of composite were confirmed by FTIR, UV–Vis, XRD and XPS. Mott–Schottky analysis was used to study the p-n heterojunction structure. The photodetection properties of ZnO NRs/PEDOS heterojunction ultraviolet photodetector were systematically investigated current–voltage (I–V) and current–time (I–t) analysis under different bias voltages. The results showed that PEDOS films uniformly grew on ZnO NRs surface and core–shell structure was formed. The p-n heterojunction structure was formed with strong built-in electric field between ZnO NRs and PEDOS. Under the irradiation of UV light, the device showed a good rectification behavior. The responsivity, detection rate and the external quantum efficiency of the ultraviolet photodetector reached to 247.7 A/W, 3.41 × 1012 Jones and 84,000% at 2 V bias, respectively. The rise time (τr) and fall time (τf) of ZnO NRs/PEDOS UV photodetector were obviously shortened compared to ZnO UV photodetector. The results show that the introduction of PEDOS effectively improves the performance of the UV photodetector.

High-Photoresponsivity Self-Powered a-, ε-, and β-Ga2O3/p-GaN Heterojunction UV Photodetectors with an In Situ GaON Layer by MOCVD.

In this paper, self-powered ultraviolet (UV) photodetectors with high response performance based on Ga2O3/p-GaN were fabricated by metal-organic chemical vapor deposition (MOCVD). The effects of different crystal phases of Ga2O3 (including a, ε, ε/β, and β) grown on p-GaN films on the performance of photodetectors were systematically studied. Moreover, an in situ GaON dielectric layer improved the responsivity of Ga2O3/p-GaN photodetectors by 20 times. All Ga2O3/p-GaN photodetectors showed self-power capability without bias. An ultralow dark current of 3.08 pA and a Iphoto/Idark ratio of 4.1 × 103 (1.8 × 103) under 254 nm (365 nm) light were obtained for the β-Ga2O3/p-GaN photodetector at 0 V bias. Furthermore, the β-Ga2O3/p-GaN photodetector showed excellent sensitivity with a high responsivity of 3.8 A/W (0.83 A/W), a fast response speed of 66/36 ms (36/73 ms), and a high detectivity of 1.12 × 1014 Jones (2.44 × 1013 Jones) under 254 nm (365 nm) light at 0 V bias. The carrier transport mechanism of the Ga2O3/p-GaN self-powered photodetector was also analyzed through the device energy band diagram. This work provides critical information for the design and fabrication of high-performance self-powered Ga2O3/p-GaN UV photodetectors, opening the door to a variety of photonic systems and applications without an external power supply.

A self-powered ZnO nanoarrays/GaN heterojunction ultraviolet photodetectors grown on Si(111) substrate

A self-powered ZnO nanoarrays/GaN heterojunction ultraviolet photodetectors grown on Si(111) substrate