Photodetector Structure Research Articles

Performance of dual-band infrared photodetectors based on M-structure superlattices

Abstract The mainstream dual-band photodetector structures are complex, requiring careful design of each absorption layer, making it difficult to customize according to specific requirements. We simplified the structure and proposed an alternative design, which based on the nBn barrier structure combined with the M-structure superlattice (M-SL). With the utmost consideration for lattice matching, we have enabled tailored design and arbitrary adjustment of the absorption coefficients for both detection bands and the overall absorption characteristics as needed. This manuscript presents a series of dual-band photodetectors. The performance of these devices was simulated at 77K, with quantum efficiency exceeding 22% in the MWIR band of the MWIR-LWIR detector, and normalized detectivity reaching 1011 cm · Hz / W . Quantum efficiency in the LWIR to VLWIR bands surpasses 19%, with normalized detectivity reaching 1011 cm · Hz / W .

AlGaN-Based Ultraviolet PIN Photodetector Grown on Silicon Substrates Using SiN Nitridation Process and Step-Graded Buffers

The integration of aluminum gallium nitride (AlGaN) with silicon substrates attracts significant attention due to the superior UV sensitivity of AlGaN and the cost-effectiveness as well as mechanical robustness of silicon. A PIN ultraviolet photodetector with a peak detection wavelength of 274 nm is presented in this paper. By employing a SiN nucleation layer and a step-graded buffer, a high-quality AlGaN-based photodetector structure with a dislocation density of 2.4 × 109/cm2 is achieved. A double-temperature annealing technique is utilized to optimize the Ohmic contact of the n-type AlGaN. The fabricated UV photodetector attains a dark current of 0.12 nA at −1 V and a peak responsivity of 0.12 A/W.

Bias‐Induced Gradient Bandgap of Bulk Perovskite Boosting Built‐In Electric Fields for High‐Performance Self‐Powered Photodetectors

AbstractSelf‐powered photodetectors (PDs) have gained significant attention in recent years due to their ability to operate without external power. Strengthening the built‐in electric field (Ebi) of these devices is crucial for efficient carrier separation and transport. However, the disordered energy level arrangement within mixed halide perovskites (MHP) often conflicts with the energy levels constructed by the external interface, weakening the Ebi and thus affecting the performance of self‐powered PDs. In this study, a bias‐induced gradient bandgap of bulk MHP is proposed for high‐performance self‐powered photodetectors. The vector superposition of the bias‐induced gradient bandgap with the interface electric field significantly boosts the Ebi of the device, providing a powerful driving force for the separation and transport of photogenerated carriers. The obtained device exhibits exceptional performance, including an ultra‐fast response time of 1.14/1.75 µs, a large specific detectivity of 7.27 × 1012 cm Hz1/2 W−1, an ultra‐high responsivity of 0.49 A W−1, and an external quantum efficiency of 93.5% at 0 V bias. Furthermore, this strategy is also demonstrated in lateral structure photodetector. This work offers valuable guidance for achieving high‐performance MHP‐based self‐powered PDs through bias‐induced gradient bandgap optimization.

Carrier dynamic identification enables wavelength and intensity sensitivity in perovskite photodetectors

Deciphering the composite information within a light field through a single photodetector, without optical and mechanical structures, is challenging. The difficulty lies in extracting multi-dimensional optical information from a single dimension of photocurrent. Emerging photodetectors based on information reconstruction have potential, yet they only extract information contained in the photoresponse current amplitude (responsivity matrix), neglecting the hidden information in response edges driven by carrier dynamics. Herein, by adjusting the thickness of the absorption layer and the interface electric field strength in the perovskite photodiode, we extend the transport and relaxation time of carriers excited by photons of different wavelengths, maximizing the spectrum richness of the edge waveform in the light-dark transition process. For the first time, without the need for extra optical and electrical components, the reconstruction of two-dimensional information of light intensity and wavelength has been achieved. With the integration of machine learning algorithms into waveform data analysis, a wide operation spectrum range of 350–750 nm is available with a 100% accuracy rate. The restoration error has been lowered to less than 0.1% for light intensity. This work offers valuable insights for advancing perovskite applications in areas such as wavelength identification and spectrum imaging.

Vertical van der Waals Integrated p‐W0.09Re0.91S2 /GaN Heterojunction for Ultra‐High Detectivity UV Image Sensing

AbstractThe relentless advancement of van der Waals (vdW) heteroepitaxy technology has charted an expansive horizon for the integration and functionalization of heterogeneous materials. In this research, a 2D/3D vdW heterojunction photodetector based on p‐W0.09Re0.91S2/n‐GaN integrated on a Free‐standing (FS)‐GaN substrate, encompassing horizontal, quasi‐vertical, and vertical structures is have successfully fabricated. By incorporating a suite of performance enhancement strategies, including mixed‐dimensional stacking, p‐type doping, type‐II band alignment, and vertical structure design, the developed vertical structure photodetector has exhibited exceptional performance. Specifically, the detector achieves a high Responsivity of up to 497.60 A W−1, an impressive specific Detectivity of 8.41 × 1013 Jones, and a fast response speed (rise/decay time of 10 ms/20 ms). Additionally, the device is successfully applied in the realm of single‐pixel imaging, substantiating its potential for practical applications. The findings of this work not only signify notable strides in integration and optoelectronic performance within the optoelectronic device domain but also portend novel breakthroughs in imaging technology applications, bestowing renewed vigor and endless potential upon the evolution of this field.

Investigation of BGaN Layer in Photodetector Structure

This study involves the design and simulation of a BGaN/GaN/ZnO/Al2O3 photodetector for UV/BLUE light with two different boron concentrations: 5% and 20%. The proposed photodetector structure exhibits an internal optical gain of 3.867 × 104 at 10 V and a wavelength of 250 nm for x = 0.05. Moreover, a gain of 1.006 × 104 at the same voltage and wavelength was obtained for a 20% boron concentration under an incidence of 0.01 × 104 cm2/W. A photocurrent peak of 0.31 mA at a wavelength of 0.455 µm, corresponding to an energy of 2.73 eV, was achieved for x = 0.05, which makes it a promising candidate for optoelectronic devices, such as light-emitting diodes (LEDs). A maximum photocurrent of 0.54 mA in the long-range deep UV range between 100 and 250 nm was obtained for x = 0.2. Based on the simulated spectral response, increasing the band gap (EG) improves the optical absorption, and higher absorption rates were found at x = 0.2 in the UV area. However, we also considered the impact of the BGaN active layer thickness on dark current and photocurrent at room temperature. Additionally, we studied the effect of temperature on current under illumination.

Impurity Level-Induced Broadband Photoelectric Response in Wide-Bandgap Semiconductor SrSnO3.

Broadband spectrum detectors exhibit great promise in fields such as multispectral imaging and optical communications. Despite significant progress, challenges like materials instability in such devices, complex manufacturing process, and high cost still hinder their further application. Here, we present a method that achieves broadband spectral detection by impurity-level in SrSnO3. We report over 500 mA/W photoresponsivity at 275 nm (ultraviolet C solar-bind) and 367 nm (ultraviolet A) and ∼60 mA/W photoresponsivity at 532 and 700 nm (visible) with a voltage bias of -5 V. Further transport and photoluminescence results reveal a new phase transition at 88 K, which would significantly affect the impurity level of the La-doped SrSnO3 film, indicating that the broadband response attributes to the impurity levels and mutual interactions. Additionally, the photodetector demonstrates excellent robustness and stability under repeated tests and prolonged exposure in air. These findings show the potential of SrSnO3 as a material for photodetectors and propose a method to achieve broadband spectrum detection, creating new possibility for the development of single-phase, low-cost, simple structure, and high-efficiency photodetectors.

Graphene-Based Field-Effect Photodetector with HgCdTe Absorber

A field-effect photodetector structure composed of an Al2O3-encapsulated bilayer graphene conductive channel attached to an Al2O3 dielectric layer deposited on a HgCdTe absorbing layer on CdTe/Si <211> was studied. Ti/Au ohmic contacts to the graphene layer were used as drain and source electrodes and back-gate voltage was applied to the Si substrate. It was demonstrated that 80% and 10% modulation of the graphene channel conductivity can be achieved under blue (50 W/cm2) and infrared (IR) (0.02 W/cm2) illumination, respectively, at a gate voltage of 7 V. Detector responsivity was measured as 406 A/W and 1.83 A/W under IR lamp and 405-nm laser irradiation, respectively, with corresponding gain values of 340 and 5.6. The detectivity of the 4 × 4 photodetector arrays was on the order of 1010 Jones for the mid-wave infrared wavelength range (3–5 μm).

High‐Performance Self‐Powered Deep Ultraviolet Photodetector Based on NiO/β‐Ga2O3 Heterojunction with High Responsivity and Selectivity

A high‐performance self‐powered deep ultraviolet (DUV) photodetector based on the NiO/β‐Ga2O3 heterojunction is fabricated and analyzed. The NiO/β‐Ga2O3 heterojunction photodetectors are fabricated both with and without a post‐annealing process following NiO film deposition. Each photodetector structure is investigated through technology computer‐aided design simulations, including energy band diagram, trap density, and carrier concentration. The pristine self‐powered NiO/β‐Ga2O3 photodetector, lacking a post‐annealing process, exhibits partial Schottky contact formation between metal and NiO film, leading to performance degradation, including reduced responsivity, detectivity, and response time. On the other hand, the post‐annealed self‐powered NiO/β‐Ga2O3 photodetector demonstrates high performance such as a responsivity of 592.0 mA W−1, a detectivity of 4.30 × 1012 Jones, and response times of 30.93 ms and 72.32 ms, respectively. Therefore, the fabricated NiO/β‐Ga2O3 photodetector shows a promising potential for various applications requiring DUV detection without an external voltage bias.

Optimal design of graphene-based plasmonic enhanced photodetector using PSO

In this paper, we report a graphene-based plasmonic photodetector optimized using the particle swarm optimization (PSO) algorithm and compatible with complementary metal–oxide–semiconductor (CMOS) technology. The proposed photodetector structure is designed to minimize fabrication challenges and reduce production costs compared to more complex alternatives. Graphene has been used for its unique properties in the detection region, titanium nitride (TiN) as a CMOS-compatible metal, and both to aid in plasmonic excitation. Photodetectors have key parameters influenced by multiple independent variables. However, practical constraints prevent thorough adjustment of all variables to achieve optimal parameter values, often resulting in analysis based on several simplified models. Here we optimize these variables by presenting a new approach in the field of photodetectors using the capabilities of the PSO algorithm. As a result, for the proposed device at the wavelength of 1550 nm, the voltage responsivity is 210.6215 V/W, the current responsivity is 3.7213 A/W, the ultra-compressed length is less than 3μm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu {\ ext{m}}$$\\end{document}, and the specific detectivity is 2.566×107\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${10}^{7}$$\\end{document} Jones were obtained. Furthermore, the device in question works under the photothermoelectric effect (PTE) at zero bias and has zero dark current, which ultimately resulted in a very low noise equivalent power (NEP) of 4.5361 pW/Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{pW}}/\\sqrt{\ ext{Hz}}$$\\end{document}.

High Performance Balanced Linear Polarization Photodetector Based on 2D ReS2

AbstractConventional research on linear polarization photodetector for 2D materials has focused on the search for different anisotropic materials, combinations between materials, introducing plasmonic structures, and patterning 2D materials to improve performance. However, these methods provide limited improvement in polarization sensitivity. Here, a balanced photodetector structure is proposed that does not require an additional process and relies only on the presence of anisotropy in the material itself to substantially improve the polarization sensitivity. The balanced photodetector consists of two ReS2 photodetectors, where the single ReS2 photodetector exhibits excellent performance at 650 nm illumination, including a responsivity and detectivity of 0.28 A W−1 and 4.22 × 109 Jones. Benefiting from the anisotropy of ReS2, the single photodetector achieves excellent polarization sensitivity of 2.79 at 650 nm. The balanced photodetector system achieves an excellent performance of ≈20 dB linear polarization extinction ratio and 0.003° Hz−1/2 noise equivalent light polarization difference at 100 kHz. These performances can also be further optimized by adjusting the gate voltage. The results provide a basis for further development of high‐performance polarization photodetector for 2D materials.

Optical and Electrical Properties of AlGaN-Based High Electron Mobility Transistors and Photodetectors with AlGaN/AlN/GaN Channel-Stacking Structure.

High channel current of the high electron mobility transistors (HEMTs) and high relative responsivity of the photodetectors (PDs) were demonstrated in the AlGaN/AlN/GaN channel-stacking epitaxial structures. The interference properties of the X-ray curves indicated high-quality interfaces of the conductive channels. The AlGaN/AlN/GaN interfaces were observed clearly in the transmission electron microscope micrograph. The saturation I ds currents of the HEMT structures were increased by adding a number of channels. The conductive properties of the channel-stacking structures corresponded to the peaks of the transconductance (g m) spectra in the HEMT structures. The depletion-mode one- and two-channel HEMT structures can be operated at the cutoff region by increasing the reverse V gs bias voltages. Higher I ds current in the active state and lower current in the cutoff state were observed in the two-channel HEMT structure compared with one- and three-channel HEMT structures. For the channel-stacking metal-semiconductor-metal photodetector structures, the peak responsivity was observed at almost 300 nm incident monochromic light, which was increased by adding a number of channel layers. The channel current of the HEMT devices and the photocurrent in the PD devices were increased by adding a number of two-dimensional electron gas (2DEG) channels. By using a flat gate metal layer, the two-channel AlGaN/AlN/GaN HEMT structures exhibited a high I ds current, a low cutoff current, and a high peak g m value and have the potential for GaN-based power devices, fast portable chargers, and ultraviolet PD applications.

Plasmonic graphene/perovskite Schottky barrier photodetector

Abstract In this paper the performance of a graphene/perovskite Schottky barrier photodetector is investigated theoretically for detecting infrared radiation within the spectral region of 7.5–10 μm. In order to increase the responsivity of the photodetector plasmon–polaritons are excited in the graphene layer within the specified spectral region with the aid of dielectric grating fabricated inside the photodetector structure. The results show that with the increase of the Fermi energy level in the graphene layer the wavelength where plasmon–polaritons are excited is shifted toward shorter wavelengths. This property enables the photodetector for tunable detection. The excitation of plasmon–polaritons localizes the infrared radiation incident on the photodetector to the graphene layer with a full width at half maximum of ≈12.6 nm. This localization increases the absorbance of the graphene layer considerably at peak detection wavelengths where plasmon–polaritons are excited, so that at peak detection wavelengths the absorbance of the graphene layer inside the photodetector is higher than 20 % while without the excitation of plasmon–polaritons the absorbance of the same layer is below 0.05 %. Due to this effect the responsivities of the photodetector at wavelengths where plasmon–polaritons are excited, increase more than 535 times relative to the case where plasmon–polaritons are not excited. Therefore the excitation of plasmon–polaritons not only increases the responsivity of the photodetector significantly but also enables the photodetector for tunable detection by varying the Fermi energy level in the graphene layer.

Automated intelligent design of modified uni-traveling carrier photodectors

This paper introduces an automatic intelligent design method for the modified uni-traveling carrier photodetector (MUTC-PD). The conventional photodetector design process often relies on the numerical solution of complex nonlinear partial differential equations to simulate and optimize device performance, which is not only computationally intensive but also inefficient. To overcome this challenge, we apply the charge control principle to calculate the photodetector bandwidth, which improves the computational speed by a factor of approximately 1800 compared to the numerical solution of nonlinear partial differential equations. To further optimize the structure of the photodetector, we incorporate the Velocity Varying Climbing Particle Swarm Optimization (VVCPSO) algorithm. This is an improved algorithm based on the traditional particle swarm algorithm, which is able to quickly find the optimal solution in a complex parameter space. By applying the VVCPSO algorithm, we successfully fine-tuned the photodetector structure and obtained structural parameters with optimal performance. Our thorough verification process confirms that the proposed method is consistent with the results of ATLAS simulation software. Automated design has resulted in a high-performance MUTC-PD with a responsivity of 0.52A/W and a bandwidth of 60 GHz (@-3 V) at a mesa diameter of 16µm. Compared to the pre-optimized device, the bandwidth is increased to three times the original. By reducing the mesa diameter to 4µm, the bandwidth can be further increased to 82 GHz (@-3 V). The proposed method's calculation speed is fast enough, enabling extensive parameter studies to optimize device performance.

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.

Performance Improvement of Formamidinium‐Based Perovskite Photodetector by Solution‐Processed C8‐BTBT Modification

AbstractOrganic–inorganic hybrid perovskite has attracted extensive research due to its excellent optoelectronic properties and is a competitive candidate material for a new generation of photodetectors. However, lateral structure photodetectors based only on perovskite active materials still present moderate performance and poor stability. Herein, lateral structure formamidinium‐based perovskite FA0.9Cs0.1PbI3 photodetectors are reported which are modified by a solution‐processed organic semiconductor 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) layer for improved photosensitive performance and ambient/flexibility stability. High‐mobility organic semiconductor C8‐BTBT serves as an efficient hole transport layer that fills the grain boundaries and gaps of the FA0.9Cs0.1PbI3 film, enabling rapid extraction and transport of the photo‐generated carriers from the perovskite to the electrodes, resulting in enhanced photosensitive performance of the photodetector. Compared with the original device, the C8‐BTBT‐modified photodetector exhibits dramatically improved performance with a best responsivity of 1278 mA W−1, specific detectivity of 1.58 × 1012 Jones, external quantum efficiency of 298%, and fall time of 14.09 ms, which is 10.84 times less than 152.76 ms of the pure perovskite device. Moreover, the C8‐BTBT film acts as a protective layer for the FA0.9Cs0.1PbI3 film because of its good air stability and effective coverage, which significantly improves the ambient stability of the perovskite photodetector compared with the original device, increasing photocurrent retention from 2.5% to 61.5% or 81.5% at different humidity after 6 days. Furthermore, the C8‐BTBT‐modified perovskite photodetector exhibits outstanding flexibility performance, with only a 5% reduction in photocurrent under bending and almost no change after 200 bending cycles, while those of the pristine perovskite device have degraded to ≈80% and ≈75% under the same conditions, respectively. This study provides a facile and effective solution‐processed‐based strategy for constructing high‐performance and stable perovskite photodetectors.

Optical properties of HgCdTe epitaxial films doped with arsenic

Subject of study. Epitaxial films of Hg0.7Cd0.3Te solid solutions grown by molecular beam epitaxy and doped with arsenic to obtain hole-type conductivity in order to form p-n junctions for the production of infrared photodetector structures are studied. Aim of study. The types and characteristics of defects formed during arsenic doping of epitaxial films of Hg0.7Cd0.3Te solid solutions grown by molecular beam epitaxy and the effect of doping on the level of disorder in the solid solution are determined. Method. Ellipsometry, optical transmittance, photoluminescence, and photoreflectance are used. Main results. The initial material is shown to have high quality in terms of film bulk and surface quality, and the quality was found to improve after two-stage activation thermal annealing. Annealing has been shown to activate the arsenic with the formation of shallow (7–8 meV) acceptor levels. No side defects were found to occur as a result of the introduction of arsenic into the films during growth and annealing. Practical significance. This research demonstrated the effectiveness of doping epitaxial films of Hg0.7Cd0.3Te solid solutions with arsenic as an acceptor impurity in order to produce layers with hole conductivity during the production of photodiode structures.

Electrical feedback system for enhancing the RF power of photodetector.

In this paper, we propose a system for enhancing the RF output power of the photodetector, especially the power of fundamental tune and second-order harmonic, by feeding back part of the RF signal through an electrical feedback circuit. As a result of bias modulation and opto-electric mixing, the RF output power can be effectively enhanced. The structure of uni-traveling carrier photodetector (UTC-PD) is employed in this work. With the RF enhancement system, the power of fundamental tune and second-order harmonic improve by 6.4 dB and 9.9 dB respectively, under the condition of 26 dBm input optical power, 3 V bias voltage, and 14 GHz input optical signal. Further, it was observed that third-order harmonic appeared under the influence of this system.

Room temperature growth of CsPbBr3 single crystal for asymmetric MSM structure photodetector

UV–visible broadband light harvesting ability is critical for photodetectors, and all inorganic perovskite CsPbBr3 is regarded as a promising candidate as the response active material. Herein, a saturated-solution crystallization method is employed to synthesize CsPbBr3 single crystal. Temperature-dependent photoluminescence spectra with one-photon and two-photon excitation are systematically investigated, determining a large exciton binding energy of 39.8 meV. This allows the stable excitonic emission of CsPbBr3 single crystal at room temperature. Subsequently, an asymmetric structure CsPbBr3 photodetector is fabricated by using InGa alloy as the Ohmic electrode and Au as the Schottky electrode. At -8 V, the device exhibits a prominent response to the irradiation from UV to green band with a maximum responsivity of 2.56 A/W, an external quantum efficiency of 580 %, and a detectivity of 1.24 × 1013 Hz1/2 W−1. In addition, the CsPbBr3 photodetector also presents rapid response speeds at both reverse and forward bias voltages and self-powered characteristics owing to the Schottky depletion layer underneath the Au electrode. The demonstration of asymmetric metal-semiconductor-metal (MSM) structure photodetector presents a promising pathway toward next-generation CsPbBr3 optoelectronic devices.

Filterless narrowband photodetectors enabled by controllable band modulation through ion migration: The case of halide perovskites

AbstractNarrowband photodetectors conventionally rely on optical structure design or bandpass filters to achieve the narrowband regime. Recently, a strategy for filterless narrowband photoresponse based on the charge collection narrowing (CCN) mechanism was reported. However, the CCN strategy requires an electrically and optically “thick” photoactive layer, which poses challenges in controlling the narrowband photoresponse. Here we propose a novel strategy for constructing narrowband photodetectors by leveraging the inherent ion migration in perovskites, which we term “band modulation narrowing” (BMN). By manipulating the ion migration with external stimuli such as illumination, temperature, and bias voltage, we can regulate in situ the energy‐band structure of perovskite photodetectors (PPDs) and hence their spectral response. Combining the Fermi energy levels obtained by the Kelvin probe force microscopy, the internal potential profiles from solar cell capacitance simulator simulation, and the anion accumulation revealed by the transient ion‐drift technique, we discover two critical mechanisms behind our BMN strategy: the extension of an optically active but electronically dead region proximal to the top electrode and the down‐bending energy bands near the electron transport layer. Our findings offer a case for harnessing the often‐annoying ion migration for developing advanced narrowband PPDs.image