High-performance Photodetectors Research Articles

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 responsivity VIS-NIR photodetector based on (PEA)2PbI4/P3HT heterojunction

Two-dimensional (2D) Ruddlesden–Popper (RP) perovskite is an ideal platform for building high-performance photodetectors due to its unique structure, excellent stability, and tunable bandgap. However, 2D perovskite heterojunction photodetectors are still less reported. In this work, the photodetector based on (PEA)2PbI4/P3HT heterojunction was prepared by the liquid-phase solution method under air conditions, which showed a responsivity (R) of 8.38 A W−1 and a specific detectivity (D*) of 6.53 × 1011Jones under 808 nm light. In addition, the device has a transient response time of 79.57 μs/484 μs and a high stability performance that maintains more than 95% of the photocurrent under continuous cycling tests and shows good cyclic stability after 30 days without encapsulation. This work provides a promising strategy for extending 2D perovskite photodetectors in the VIS to NIR spectral range.

High-performance solar-blind photodetectors based on Ta-doped ZnSnO3 single crystal thin films

High-quality Ta-doped ZnSnO3 single crystal thin films were grown on LiTaO3 substrates by pulsed laser deposition (PLD) method, and the effects of Ta doping on the lattice structure, surface morphology, electronic structure and photodetector performance of ZnSnO3 thin films are studied in detail. When the Ta doping content is 1 %, the [0001]-oriented ZnSnO3 thin film present the highest quality, which the optical band gap (3.75 eV), the smoothest surface roughness (0.83 nm), and the biggest carrier concentration (4.03 × 1019 cm−3). For the solar-blind photodetectors (PDs), based on these excellent characteristics, the 1 % Ta-doped ZnSnO3 PD exhibits large light-to-dark current ratio (>103), responsivity (21.37 A/W), detectivity ((3.63±0.71) ×1011 Jones) and external quantum efficiency (∼1.04× 104 %) under 254 nm UV light at an applied bias of 5 V. This study suggests that Ta doping can effectively improve the optoelectronic performance of ZnSnO3 PDs, laying the foundation for their application.

High-performance GeSi/Ge multi-quantum well photodetector on a Ge-buffered Si substrate.

This work demonstrates a high-performance photodetector with a 4-cycle Ge0.86Si0.14/Ge multi-quantum well (MQW) structure grown by reduced pressure chemical vapor deposition techniques on a Ge-buffered Si (100) substrate. At -1 V bias, the dark current density of the fabricated PIN mesa devices is as low as 3 mA/cm2, and the optical responsivities are 0.51 and 0.17 A/W at 1310 and 1550 nm, respectively, corresponding to the cutoff wavelength of 1620 nm. At the same time, the device has good high-power performance and continuous repeatable light response. On the other hand, the temperature coefficient of resistance (TCR) of the device is as high as -5.18%/K, surpassing all commercial thermal detectors. These results indicate that the CMOS-compatible and low-cost Ge0.86Si0.14/Ge multilayer structure is promising for short-wave infrared and uncooled infrared imaging.

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.

Enhanced photovoltaic response in WSe2 photodetector with asymmetric two-dimensional contacts

Asymmetric contact pairs with different work functions provide an efficient method to extract photogenerated carriers in optoelectrical devices. Specifically, vertical optoelectrical devices based on two-dimensional (2D) materials utilize graphene layers as the bottom and top contacts. Whereas an additional terminal is required for electrostatic doping in either top or bottom graphene to enlarge the built-in electric field. Herein, we present an enhanced photovoltaic response in a vertical WSe2 photodetector utilizing asymmetric 2D contacts. A graphite layer and a degenerate SnSe2 are used as the top and bottom contacts, respectively, with a significant difference in their work functions. By establishing a large built-in electric field across the vertical WSe2 layer, a strong photovoltaic effect is achieved, resulting in an open-circuit voltage of 0.37 V and a short-circuit current of 0.42 μA under 532 nm illumination. The device shows high-performance photodetection characteristics, with a responsivity of 32.04 A W−1, external quantum efficiency of 7475%, and specific detectivity of 3.61 × 1012 Jones. Furthermore, the device can generate a maximum output electrical power of 70.9 nW, enabling a high-power conversion efficiency of 3.5%.

Template-Confined Oriented Perovskite Nanowire Arrays Enable Polarization Detection and Imaging.

Polarized light detection can effectively identify the difference between the polarization information on the target and the background, which is of great significance for detection in complex natural environments and/or extreme weather. Generally, polarized light detection inevitably relies on anisotropic structures of photodetector devices, while organic-inorganic hybrid perovskites are ideal for anisotropic patterning due to their simple and efficient preparation by solution method. Compared to patterned thin films, patterned arrays of aligned one-dimensional (1D) perovskite nanowires (PNWAs) have fewer grain boundaries and lower defect densities, making them well suited for high-performance polarization-sensitive photodetectors. Here, we fabricated PNWAs crystallographically aligned with variable line widths and alignment densities employing CD-ROM and DVD-ROM grating pattern template-confined growth (TCG) methods. The photodetectors constructed from MAPbI3 PNWAs achieved responsivity of 35.01 A/W, detectivity of 6.85 × 1013 Jones, and fast response with a rise time of 172 μs and fall time of 114 μs. They were successfully applied to high-performance polarization detection with a polarization ratio of 1.81, potentially applicable in polarized light detection systems.

Hysteresis, Impedance, and Transients Effects in Halide Perovskite Solar Cells and Memory Devices Analysis by Neuron‐Style Models

AbstractHalide perovskites are at the forefront of active research in many applications, such as high performance solar cells, photodetectors, and synapses and neurons for neuromorphic computation. As a result of ion transport and ionic‐electronic interactions, current and recombination are influenced by delay and memory effects that cause hysteresis of current–voltage curves and long switching times. A methodology to formulate device models is shown, in which the conduction and recombination electronic variables are influenced by internal state variables. The models are inspired in biological frameworks of the Hodgkin–Huxley class of models. Here, the theoretical precedents, the main physical components of the models, and their application to describe dynamical measurements in halide perovskite devices are summarized. The application of several measurement methods is analyzed, as the current–voltage curves at different scan rates, the impedance spectroscopy response, and the time transients. The transition from normal (capacitive) to inverted (inductive) hysteresis, and the convergence of current–voltage curves to a stable value, are described. It is proposed that neuron‐style models capture dynamical complexity with a favorable economy of parameters, toward the identification of the dominant global dynamic processes across a wide voltage span that determines the practical response of different types of devices.

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.

Significantly improved optoelectronic performances of two-dimensional WS2(Er3+)/WSe2(Er3+) van der waals heterojunctions

Two-dimensional heterostructures with excellent properties are potential for high performance optoelectronic applications, since the ultimate thickness limit is possible to be broken with the advent of atomically thin materials. Yet the studies have also been largely constrained by the low physical doping space and absorption rates due to the atomic-thickness layers, and the efforts for high carrier concentrations and gain remain a significant challenge. Herein, high concentration of Er3+ ions are in-situ doped in WS2 and WSe2 atomic layers by chemical vapor deposition (CVD) method. The prepared layers are characterized by atomic force microscopy, transmission electron microscopy, photoluminescence (PL) spectroscopy, and Raman spectroscopy, respectively. 13–14 at% of Er3+ doping concentration in WSe2 and WS2 are examined by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) with high consistency. A microregion fixed-point transfer technique is used to transfer the WS2(Er3+) monolayers onto the WSe2(Er3+) monolayers to form vertical van der Waals heterojunctions. Excellent performances are measured from the WS2(Er3+)/WSe2(Er3+) photodetector with the photoresponsivity of up to 67.4 A/W, external quantum efficiency of 13,202 %, and detectivity of 7.07 × 1011 Jones. Our results prove the effectiveness of Er3+ in-situ doping in WS2(Er3+)/WSe2(Er3+) heterojunctions for high-performance photodetectors.

Symmetry-Reduction Enhanced Polarization-Sensitive Photoresponse Based on One-Dimensional van der Waals Materials.

Designing high-performance polarization-sensitive photodetectors is essential for photonic device applications. Anisotropic one-dimensional (1D) van der Waals (vdW) materials have provided a promising platform to that end. Despite significant advances in 1D vdW photonic devices, their performance is still far from delivering practical potential. Herein, we propose the design of high-performance polarization-sensitive photodetectors using unique 1D vdW materials. By leveraging the chemical vapor transport technique, we successfully fabricate high-quality 1D vdW Nb2Pd1-xSe5 (x = 0.29) nanowires. The 1D vdW Nb2Pd1-xSe5 photodetector exhibits a high mobility of ∼56 cm2/(V s) and superior photoresponse performance, including a high responsivity of 1A/W and an ultrafast response time of ∼8 μs under 638 nm illumination. Moreover, the 1D vdW Nb2Pd1-xSe5 photodetector demonstrates excellent polarization-sensitive photoresponse with a degree of linear polarization (DOLP) up to 0.85 and can be modulated by adjusting the gate voltage, laser power density, and wavelength. Those exceptional performance are believed to be relevant to the symmetry-reduction induced by the partial occupation of Pd sites. This study offers feasible approaches to enhance the anisotropy of 1D vdW materials and the modulation of their polarization-sensitive photoresponse, which may provide deep insights into the physical origin of anisotropic properties of 1D vdW materials.

Detecting Visible to Near-Infrared II Light via CsPbBr3 Nanocrystals/Y6 Heterojunctions.

In the endeavor to develop advanced photodetectors (PDs) with superior performance, all-inorganic perovskites, recognized for their outstanding photoelectric properties, have emerged as highly promising materials. Due to their unique electronic structure and band characteristics, the majority of all-inorganic perovskite materials are not sensitive to near-infrared (NIR) light. Here, we demonstrate the fabrication of a high-performance broadband PD comprising CsPbBr3 perovskite NCs/Y6 planar heterojunctions. The incorporation of Y6 not only facilitates charge transfer from CsPbBr3 NCs to Y6 for enhancing photodetection performance under visible illumination but also broadens the absorption spectrum range of the whole device toward the NIR regime. As a result, the heterojunction PD exhibits a photo-to-dark-current ratio above 105, a dynamic range of 149.5 dB, and an impressive lowest detection limit of incident power density of 1.6 nW/cm2 under 505 nm illumination. In the NIR regime, where photon energy is below the bandgap of CsPbBr3, electron-hole pairs can still be produced in the Y6 layer even when illuminated at 1120 nm. Consequently, photodetection is uniquely possible in PDs that incorporate heterojunctions when the illumination wavelength is longer than 565 nm. At 850 nm, the heterojunction device is capable of detecting light with power densities as low as 1.3 μW/cm2 corresponding to a LDR of 99.8 dB. The exceptional performance is attributed to the creation of a heterojunction between CsPbBr3 NCs and Y6. These findings propose a novel approach for developing broadband PDs based on perovskite NC materials.

Development of high-performance ultrafast photodetector using CsPbBr3 perovskite single crystal

Here, we have developed a high-performance photodetector with enhanced photoelectric conversion efficiency and rapid response kinetics using an inorganic CsPbBr3 perovskite single crystal (PSC). A large area of high-quality PSC has been synthesized using a novel modified inverse temperature crystallization (ITC) process. The formation of the single crystal of the CsPbBr3 perovskite in an orthorhombic phase was confirmed by the X-ray diffraction (XRD) spectra while the excellent light absorption characteristics are corroborated with UV-Vis studies. A proposed Metal-Semiconductor-Metal (M-S-M) photodetector device structure using the CsPbBr3 PSC (Au/CsPbBr3/Au) has been examined by using monochromatic light in a wavelength range of 350–700 nm. The PSC photodetector exhibits excellent spectral responsivity of ∼ 0.42 A/W, detectivity of 6.26 × 1010 Jones, and external quantum efficiency of ∼ 95% with an ultrafast response/recovery time of ∼ 40/35 ms. Such excellent results unveil a new perspective in the PSC-based next-generation optoelectronic devices.

Two-dimensional CuSe nanosheet array for high-performance photoelectrochemical photodetector using simulated seawater as electrolyte

Photoelectrochemical-type (PEC) photodetectors (PDs) show great promise in underwater optoelectronic devices, but most reports of PEC PDs use acid or basic solutions as electrolytes, hindering their practical application in marine scenarios. In this letter, we reported high-performance 2D CuSe-based PEC PDs with use of the electrolyte of simulated seawater for the first time. The 2D CuSe nanosheet array (NSA) is synthesized by a facile electrodeposition method. The PEC PDs based on 2D CuSe NAS has a superior responsivity of 9.5 mA/W for 455 nm light in the simulated seawater, and exhibits a broadband photoresponse in 365–850 nm, surpassing most TMCs-based PEC PDs. The superior photoresponse originates from the vertical NSA structure, providing more interfacial active sites and higher light absorption. In addition, 2D CuSe NSA-based PEC PDs possess self-powered ability, fast response speed, good stability, and underwater optical communication capability. This work demonstrates the great potential of 2D CuSe NSA in PEC-type optoelectronic devices.

Sputtered Sn-doped Ga2O3 films under balance controlled of energy supply and ion bombardment for solar-blind detection application

The characteristics of amorphous Sn-doped Ga2O3 films deposited using radio frequency magnetron sputtering at room temperature under different sputter powers have been demonstrated. A balance mechanism of energy supply and ion bombardment controlled by sputter power has been found during the deposition. The increasing growth rate as power can be due to the increased yield sputtering species indicated by an in situ optical emission spectroscopy. As the power increases to 700 W, an obvious change from discrete nanoparticles to flat-continuous film can be observed because of sufficient energy supply for oxidation reaction, which leads to the maximum ratio of lattice oxygen and Sn4+ indicating the optimal film quality and conductive property. However, a non-negligible high energy ion bombardment presented at 900 W leads to the degraded film quality. The influence of sputtering power on Sn-doped Ga2O3 solar-blind photodetectors is demonstrated. It can obtain a good performance with an ultra-low dark current density of 2.2 × 10−11 A/cm2, a substantial light-dark current ratio of 1.08 × 103 and fast rise/decay time of 1.59 s/0.54 s at 700 W. The revelation of the role of sputtering power on the properties of Sn-doped Ga2O3 films may offer an interesting direction for low-cost and high-performance solar-blind photodetectors.

High-performance photodetection based on black arsenic utilizing photoconductive effect

High-performance photodetection based on black arsenic utilizing photoconductive effect

Uncooled Broadband Photodetection via Light Trapping in Conformal PtTe2-Silicon Nanopillar Heterostructures.

Dirac semimetals have demonstrated significant attraction in the field of optoelectronics due to their unique bandgap structure and high carrier mobility. Combining them with classical semiconductor materials to form heterojunctions enables broadband optoelectronic conversion at room temperature. However, the low light absorption of layered Dirac semimetals substantially limits the device's responsivity in the infrared band. Herein, a three-dimensional (3D) heterostructure, composed of silicon nanopillars (SiNPs) and a conformal PtTe2 film, is proposed and demonstrated to enhance the photoresponsivity for uncooled broadband detection. The light trapping effect in the 3D heterostructure efficiently promotes the interaction between light and PtTe2, while also enhancing the light absorption efficiency of silicon, which enables the enhancement of the device responsivity across a broadband spectrum. Experimentally, the PtTe2-SiNPs heterojunction device demonstrates excellent photoelectric conversion behavior across the visible, near-infrared, and long-wave infrared (LWIR) bands, with its responsivity demonstrating an order-of-magnitude improvement compared to the counterparts with planar silicon heterojunctions. Under 11 μm laser irradiation, the noise equivalent power (NEP) can reach 1.76 nW·Hz-1/2 (@1 kHz). These findings offer a strategic approach to the design and fabrication of high-performance broadband photodetectors based on Dirac semimetals.

Heterojunctions of Mercury Selenide Quantum Dots and Halide Perovskites with High Lattice Matching and Their Photodetection Properties.

Heterojunction semiconductors have been extensively applied in various optoelectronic devices due to their unique carrier transport characteristics. However, it is still a challenge to construct heterojunctions based on colloidal quantum dots (CQDs) due to stress and lattice mismatch. Herein, HgSe/CsPbBrxI3-x heterojunctions with type I band alignment are acquired that are derived from minor lattice mismatch (~1.5%) via tuning the ratio of Br and I in halide perovskite. Meanwhile, HgSe CQDs with oleylamine ligands can been exchanged with a halide perovskite precursor, acquiring a smooth and compact quantum dot film. The photoconductive detector based on HgSe/CsPbBrxI3-x heterojunction presents a distinct photoelectric response under an incident light of 630 nm. The work provides a promising strategy to construct CQD-based heterojunctions, simultaneously achieving inorganic ligand exchange, which paves the way to obtain high-performance photodetectors based on CQD heterojunction films.

Activation of the Photosensitive Potential of 2D GaSe by Interfacial Engineering.

Two-dimensional (2D) gallium selenide (GaSe) holds great promise for pioneering advancements in photodetection due to its exceptional electronic and optoelectronic properties. However, in conventional photodetectors, 2D GaSe only functions as a photosensitive layer, failing to fully exploit its inherent photosensitive potential. Herein, we propose an ultrasensitive photodetector based on out-of-plane 2D GaSe/MoSe2 heterostructure. Through interfacial engineering, 2D GaSe serves not only as the photosensitive layer but also as the photoconductive gain and passivation layer, introducing a photogating effect and extending the lifetime of photocarriers. Capitalizing on these features, the device exhibits exceptional photodetection performance, including a responsivity of 28 800 A/W, specific detectivity of 7.1 × 1014 Jones, light on/off ratio of 1.2 × 106, and rise/fall time of 112.4/426.8 μs. Moreover, high-resolution imaging under various wavelengths is successfully demonstrated using this device. Additionally, we showcase the generality of this device design by activating the photosensitive potential of 2D GaSe with other transition metal dichalcogenides (TMDCs) such as WSe2, WS2, and MoS2. This work provides inspiration for future development in high-performance photodetectors, shining a spotlight on the potential of 2D GaSe and its heterostructure.

Controlled Synthesis of Ultrathin Cu2Te Nanosheets for High-Performance Photodetectors

Controlled Synthesis of Ultrathin Cu₂Te Nanosheets for High-Performance Photodetectors