Integration Of Optoelectronic Devices Research Articles

Graphene-Perovskite Fibre Photodetectors.

The integration of optoelectronic devices, such as transistors and photodetectors (PDs), into wearables and textiles is of great interest for applications such as healthcare and physiological monitoring. These require flexible/wearable systems adaptable to body motions, thus materials conformable to non-planar surfaces, and able to maintain performance under mechanical distortions. Here, weprepare fibre PDs combining rolled graphene layers and photoactive perovskites. Conductive fibres (∼500 Ω/cm) are made by rolling single-layer graphene (SLG) around silica fibres, followed by deposition of a dielectric layer (Al2O3 and parylene C), another rolled SLG as a channel, and perovskite as photoactive component. The resulting gate-tunable PD has a response time∼9ms, with an external responsivity∼22kA/W at 488nm for a 1V bias. The external responsivity is two orders of magnitude higher, and the response time one order of magnitude faster, than state-of-the-art wearable fibre-based PDs. Under bending at 4mm radius, up to∼80% photocurrent is maintained. Washability tests show∼72% of initial photocurrent after 30 cycles, promising for wearableapplications. This article is protected by copyright. All rights reserved.

Enhancement-Mode Carbon Nanotube Optoelectronic Synaptic Transistors with Large and Controllable Threshold Voltage Modulation Window for Broadband Flexible Vision Systems.

The development of large-scale integration of optoelectronic neuromorphic devices with ultralow power consumption and broadband responses is essential for high-performance bionics vision systems. In this work, we developed a strategy to construct large-scale (40 × 30) enhancement-mode carbon nanotube optoelectronic synaptic transistors with ultralow power consumption (33.9 aJ per pulse) and broadband responses (from 365 to 620 nm) using low-work function yttrium (Y)-gate electrodes and the mixture of eco-friendly photosensitive Ag2S quantum dots (QDs) and ionic liquids (ILs)-cross-linking-poly(4-vinylphenol) (PVP) (ILs-c-PVP) as the dielectric layers. Solution-processable carbon nanotube thin-film transistors (TFTs) showed enhancement-mode characteristics with the wide and controllable threshold voltage window (-1 V∼0 V) owing to use of the low-work-function Y-gate electrodes. It is noted that carbon nanotube optoelectronic synaptic transistors exhibited high on/off ratios (>106), small hysteresis and low operating voltage (≤2 V), and enhancement mode even under the illumination of ultraviolet (UV, 365 nm), blue (450 nm), and green (550 nm) to red (620 nm) pulse lights when introducing eco-friendly Ag2S QDs in dielectric layers, demonstrating that they have the strong fault-tolerant ability for the threshold voltage drifts caused by various manufacturing scenarios. Furthermore, some important bionic functions including a high paired pulse facilitation index (PPF index, up to 290%), learning and memory function with the long duration (200 s), and rapid recovery (2 s). Pavlov's dog experiment (retention time up to 20 min) and visual memory forgetting experiments (the duration of high current for 180 s) are also demonstrated. Significantly, the optoelectronic synaptic transistors can be used to simulate the adaptive process of vision in varying light conditions, and we demonstrated the dynamic transition of light adaptation to dark adaptation based on light-induced conditional behavior. This work undoubtedly provides valuable insights for the future development of artificial vision systems.

The Interaction of Femtosecond Laser with Perovskites for Advanced Photonics

Halide perovskites have attracted increasingly attention as “rising star” materials for advanced photonics and optoelectronics. Construction micro‐/nano‐architecture of perovskites will provide a good platform to investigate and optimize the fundamental photon–matter–structure interaction. It will also improve the properties, pixelate and miniaturize the integration of versatile optoelectronic devices for emerging applications. In this regard, femtosecond (fs) laser processing technique has been widely used to fabricate micro‐/nano‐architecture with high spatial resolution, limitless flexibility, and unrestricted three‐dimensional structuring capability at a large‐scale, low‐cost way. Concurrently, it is reported that the high refractive index, low thermal conductivity and ultrafast thermalization rate of perovskites are beneficial for the processing by fs laser into micro‐/nano‐architecture without the degradation of their optoelectronic properties. This review systematically summarizes the interaction of fs laser with perovskites, including the mechanisms, and phenomena. Besides the traditional optoelectronics and applications of halide perovskites, the novel properties and applications from optical structures generated by fs laser processing of perovskites are also discussed. The challenges and outlooks for fs laser processed perovskite materials and devices are highlighted. This review will promote the relevant fundamental research on light–matter–structure interaction, and facilitate the integration of perovskite micro‐/nano‐architecture‐based optoelectronic devices.

Large‐Scale Ultrastable 2D Inorganic Molecular Crystal BiBr3 and Heterostructures with Superior Photoluminescence Enhancement

AbstractIn contrast to conventional atomic crystals, two‐dimensional inorganic molecular crystals (2DIMCs) possess a unique crystal structure composed of small molecules held together by van der Waals force. Such distinctive structure grants them specific chemical and physical properties highly suitable for electronic and optoelectronic applications. However, the synthesis of 2DIMCs has posed significant challenges due to the inherent issues such as uncontrollable growth orientation stemming from their natural crystalline isotropy and poor stability resulting from the weak intermolecular connections. Addressing these obstacles, the preparation of large‐scale and highly‐stable 2DIMC BiBr3, and its heterostructure are reported here by developing crystallization orientation engineering strategies. This approach has successfully yielded centimeter‐scale 2DIMC BiBr3 with a clean and dense surface, showcasing exceptional long‐term air‐stability exceeding 80 days. Furthermore, the universal growth of large‐scale 2DIMC BiBr3 is demonstrated on diverse substrates, including SiO2, Al2O3, and MoS2 monolayers. Notably, the resultant 2D BiBr3/MoS2 heterostructure exhibits remarkable photoluminescence enhancement. This contribution paves a universal avenue for the mature synthesis of large‐scale 2DIMCs with superior stability, holding great promise for prompting their integration in practical electronic and optoelectronic devices.

Broadband Photodetection of Centimeter-Scale T-Phase Gallium Telluride Grown by Molecular Beam Epitaxy.

Two-dimensional (2D) semiconductors have recently attracted considerable attention due to their promising applications in future integrated electronic and optoelectronic devices. Large-scale synthesis of high-quality 2D semiconductors is an increasingly essential requirement for practical applications, such as sensing, imaging, and communications. In this work, homogeneous 2D GaTe films on a centimeter scale are epitaxially grown on fluorphlogopite mica substrates by molecular beam epitaxy (MBE). The epitaxial GaTe thin films showed an atomically 2D layered lattice structure with a T phase, which has not been discovered in the GaTe geometric isomer. Furthermore, semiconducting behavior and high mobility above room temperature were found in T-GaTe epitaxial films, which are essential for application in semiconducting devices. The T-GaTe-based photodetectors demonstrated respectable photodetection performance with a responsivity of 13 mA/W and a fast response speed. By introducing monolayer graphene as the substrate, we successfully realized high-quality GaTe/graphene heterostructures. The performance has been significantly improved, such as the responsivity was enhanced more than 20 times. These results highlight a feasible scheme for exploring the crystal phase of 2D GaTe and realizing the controlled growth of GaTe films on large substrates, which could promote the development of broadband, high-performance, and large-scale photodetection applications.

Intercorrelated Ferroelectricity and Bulk Photovoltaic Effect in Two-Dimensional Sn2P2S6 Semiconductor for Polarization-Sensitive Photodetection.

A two-dimensional (2D) ferroelectric semiconductor, which is coupled with photosensitivity and room-temperature ferroelectricity, provides the possibility of coordinated conductance modulation by both electric field and light illumination and is promising for triggering the revolution of optoelectronics for monolithic multifunctional integration. Here, we report that semiconducting Sn2P2S6 crystals can be achieved in a 2D morphology using a chemical vapor transport approach with the assistant of space confinement and experimentally demonstrate the robust ferroelectricity in atomic-thin Sn2P2S6 nanosheet at room temperature. The intercorrelated programming of ferroelectric order along out-of-plane (OOP) and in-plane (IP) directions enables a tunable bulk photovoltaic (BPV) effect through multidirectional electrical control. By combining the capability of anisotropic in-plane optical absorption, a highly integrated Sn2P2S6 optoelectronic device vertically sandwiched with graphene electrodes yields the polarization-dependent open-circuit photovoltage with a dichroic ratio of 2.0 under 405 nm light illumination. The reintroduction of ferroelectric Sn2P2S6 to the 2D asymmetric semiconductor family provides possibilities to hardware implement of the self-powered polarization-sensitive photodetection and spotlights the promising applications for next-generation photovoltaic devices.

Organic‐Inorganic Hybrid Ferroelectric and Antiferroelectric with Afterglow Emission

AbstractLuminescent ferroelectrics are holding exciting prospect for integrated photoelectronic devices due to potential light‐polarization interactions at electron scale. Integrating ferroelectricity and long‐lived afterglow emission in a single material would offer new possibilities for fundamental research and applications, however, related reports have been a blank to date. For the first time, we here achieved the combination of notable ferroelectricity and afterglow emission in an organic‐inorganic hybrid material. Remarkably, the presented (4‐methylpiperidium)CdCl3 also shows noticeable antiferroelectric behavior. The implementation of cationic customization and halogen engineering not only enables a dramatic enhancement of Curie temperature of 114.4 K but also brings a record longest emission lifetime up to 117.11 ms under ambient conditions, realizing a leapfrog improvement of at least two orders of magnitude compared to reported hybrid ferroelectrics so far. This finding would herald the emergence of novel application potential, such as multi‐level density data storage or multifunctional sensors, towards the future integrated optoelectronic devices with multitasking capabilities.

Organic-Inorganic Hybrid Ferroelectric and Antiferroelectric with Afterglow Emission.

Luminescent ferroelectrics are holding exciting prospect for integrated photoelectronic devices due to potential light-polarization interactions at electron scale. Integrating ferroelectricity and long-lived afterglow emission in a single material would offer new possibilities for fundamental research and applications, however, related reports have been a blank to date. For the first time, we here achieved the combination of notable ferroelectricity and afterglow emission in an organic-inorganic hybrid material. Remarkably, the presented (4-methylpiperidium)CdCl3 also shows noticeable antiferroelectric behavior. The implementation of cationic customization and halogen engineering not only enables a dramatic enhancement of Curie temperature of 114.4 K but also brings a record longest emission lifetime up to 117.11 ms under ambient conditions, realizing a leapfrog improvement of at least two orders of magnitude compared to reported hybrid ferroelectrics so far. This finding would herald the emergence of novel application potential, such as multi-level density data storage or multifunctional sensors, towards the future integrated optoelectronic devices with multitasking capabilities.

Single-layer and bilayer In2SeO2: Direct bandgap and reduced exciton binding from first-principles calculation

Two-dimensional semiconductors having direct bandgaps and weak exciton binding are necessary for highly integrated optoelectronic devices. Herein, single-layer (SL) and bilayer (AA and AB) In2SeO2 are proposed for the first time and studied using first-principles calculations. Both SL and bilayer In2SeO2 are of experimental feasibility for good stability. SL and bilayer AB In2SeO2 show moderate direct bandgaps at the HSE06 level. Their abundant visible-light absorption and weak exciton binding promise the successful generation of separated carriers. The high electron mobility of SL (∼3000 cm2·V−1·s−1) and bilayer AB (∼2600 cm2·V−1·s−1) suggests the possible application in electronics. The effective separation of electrons and holes is further confirmed by the huge discrepancy in carrier mobility and long-lived charge carriers. Summarily, our calculations support that In2SeO2 is a promising candidate in ultrathin optoelectronic devices.

Electrically tunable dual polarization states of light using lithium niobate-based nanograting.

Tuning polarization states of light electrically has unique advantages in the integration of optoelectronic devices. Here, a lithium niobate-based nanograting is proposed to dynamically tune the polarization state of both the reflected and transmitted lights simultaneously in the near-infrared range. By judiciously designing the nanograting, a quasi-bound state in the continuum (qBIC) is excited under the excitation of an obliquely incident plane wave. The excited mode with a high quality-factor and enhanced local electric field can respond to a refractive index change in nanograting structures as small as 10-4 level, which can be generated with a low external voltage via the electro-optic effect. As a result, both the polarization states of reflected and transmitted lights can be dynamically tuned from a right circular polarization to a linear polarization state. The proposed lithium niobate-based nanograting for tuning dual polarization states of light with a qBIC mode suggests a promising electrical scheme for achieving high speed optoelectronic devices.

On-chip organic optoelectronic system for fluorescence detection

A single and miniaturized fluorescence sensor is obtained by the vertical integration of organic optoelectronic devices and organic photonic components.

Stability and photocurrent enhancement of photodetectors by using core/shell structured CsPbBr3/TiO2 quantum dots and 2D materials.

Ultra-stable CsPbBr3 perovskite quantum dots (QDs) were prepared, and the performance of the photodetector fabricated from them was enhanced by 2D material incorporation. This multi-component photodetector appears to have good stability in the ambient utilization environment. All inorganic CsPbBr3 QDs are potential candidates for application in photodetection devices. However, QDs have several issues such as defects on the QD surface, degradation under environmental conditions, and unfavorable carrier mobility limiting the high performance of the photodetectors. This work addresses these issues by fabricating a core/shell structure and introducing 2D materials (MXenes, Ti3C2Tx) into the device. Here, three types of photodetectors with QDs only, QDs with a core/shell structure, and QDs with a core/shell structure and MXenes are fabricated for systematic study. The CsPbBr3/TiO2 photodetector demonstrated a two times photocurrent enhancement compared to bare QDs and had good device stability after TiO2 shell coating. After introducing Ti3C2Tx into CsPbBr3/TiO2, a significant photocurrent enhancement from nanoampere (nA) to microampere (μA) was observed, revealing that MXenes can improve the photoelectric response of perovskite materials significantly. Higher photocurrent can avoid signal interference from environmental noise for better practical feasibility. This study provides a systematic understanding of the photocurrent conversion of perovskite quantum dots that is beneficial in advancing optoelectronic device integration, especially for flexible wearable device applications.

Photonic post-processing of a multi-material transparent conductive electrode architecture for optoelectronic device integration.

Emerging flexible optoelectronic devices require multi-material processing capabilities to fully enable the use of temperature-sensitive substrates and materials. This report demonstrates how photonic sintering enables the processing of materials with very different properties. For example, charge carrier transport/blocking metal-oxides, and transparent conductive silver nanowire-based electrodes ought to be compatible with low-energy and high-throughput processing for integration onto flexible low-temperature substrates. Compared to traditional post-processing methods, we show a rapid fabrication route yielding highly-stable hybrid electrode architectures on polyethylene terephthalate (PET). This architecture consists of an interconnected silver nanowire network encapsulated with a thin crystalline photo-sensitive titanium dioxide (TiO2) coating, allowing both layers to be treated using independent photonic post-processing sintering steps. The first step sinters the nanowires, while the second completes the conversion of the top metal-oxide layer from amorphous to crystalline TiO2. This approach improves on the fabrication speed compared to oven processing, while delivering optical and electrical characteristics comparable to the state of the art. Optimized transparency values reach 85% with haze values down-to 7% at 550 nm, while maintaining a sheet resistance of 18.1 Ω sq.-1. However, this hybrid architecture provides a much stronger resilience to degradation, which we demonstrate through exposure to harsh plasma conditions. In summary, this study shows how carefully-optimized photonic curing post-processing can provide more-stable hybrid architectures while using a multi-material processing technique suitable for high-volume manufacturing on low-temperature substrates.

Recent Development of Lens Array Fabrication: A Review

The lens array is a multi-functional optical element, which can modulate the incident light such as diffusion, beam shaping, light splitting, and optical focusing, thereby achieving large viewing angle, low aberration, small distortion, high temporal resolution, and infinite depth of field. Meanwhile, it has important application potential in the form, intelligence and integration of op-to electronic devices and optical systems. In this paper, the optical principle and development history of lens arrays are introduced, and the lens array fabrication technologies such as ink jet printing, laser direct writing, screen printing, photo lithography, photo polymerization, hot melt reflow and chemical vapor deposition are reviewed. The application progress of lens arrays in imaging sensing, illumination light source, display and photovoltaic fields is presented. And this paper prospected the development direction of lens arrays, and discussed the development trends and future challenges of new directions such as curved lenses, superimposed compound eye systems, and the combination of lenses and new op-to electronic materials.

Quantum Cascade Lasers Grown by Metalorganic Chemical Vapor Deposition on Foreign Substrates with Large Surface Roughness

The surface morphology of a buffer template is an important factor in the heteroepitaxial integration of optoelectronic devices with a significant lattice mismatch. In this work, InP-based long-wave infrared (~8 µm) emitting quantum cascade lasers with active region designs lattice-matched to InP were grown on GaAs and Si substrates employing InAlGaAs step-graded metamorphic buffer layers, as a means to assess the impact of surface roughness on device performance. A room-temperature pulsed-operation lasing with a relatively good device performance was obtained on a Si template, even with a large RMS roughness of 17.1 nm over 100 µm2. Such results demonstrate that intersubband-operating devices are highly tolerant to large RMS surface roughness, even in the presence of a high residual dislocation density.

Tailoring the optoelectronic, thermoelectric, and thermodynamic properties of rare-earth quaternary chalcogenides: An inclusive first-principles study

The exceptional optoelectronic properties of quaternary chalcogenides have aroused a great deal of interest, especially for their potential application in most optoelectronic devices. Here, we investigated the diverse physical properties of novel BaQCuS3 (Q = Er and Gd) semiconductors by employing the density functional theory. The predicted band structures show that the compounds under investigation exhibit indirect band gaps. From the predicted density of states, the low energy levels of the Cu-d orbitals and their involvement in bonding and antibonding states with nearby atoms enable them to contribute to the valence band. The components of the complex dielectric function, absorption coefficients, real optical conductivity, energy loss functions, refractive index, reflectivity, and extinction coefficient, are also computed and explained to determine their potential usage in optoelectronic devices. We also calculated the thermoelectric transport parameters of these materials and discussed them in detail. The significant thermodynamic properties are also predicted to predict the stability of these compounds. The attained results in this work will have a substantial impact on the growth of effective integrated optoelectronic devices and the scope of their useful applications.

Influence of Building Block Symmetry on the Band Structure of Stacked 2D Polyimide Covalent Organic Frameworks.

Covalent organic frameworks (COFs) are a class of crystalline porous materials distinctively built solely from organic elements, carbon, oxygen, hydrogen, and often nitrogen or boron. They form light, mechanically rigid, and chemically stable networks that have many advantages, but their low solubility and poor processability create issues with developing large-scale films or membranes. Two-dimensional (2D) COFs possess periodic porous crystallinity, functionality, modularity, and layered one-dimensional (1D) transport channels. All of these traits, along with the semiconducting properties of selected COFs, make them interesting candidates for integration in optoelectronic devices. Therefore, it is still a challenge to explore computationally and structurally the semiconductivity of COFs and to determine their final potential. Herein, we report on the possible semiconducting properties and results of polyimide-COF materials using density functional theory calculations. Our analysis includes monolayers and multilayers (AA- and AB-stacked modes) of mellitic triimide frameworks designed from mellitic trianhydride (MTA) as the main building knot, including MTI-TAPB-COF, which was previously synthesized from the condensation reaction of MTA and 1,3,5-tris(4-aminophenyl)benzene (TAPB), and other previously unreported structures based on MTA. Respective frameworks have been selected due to the difference in building block symmetry (C3 + C2 and C3 + C3) and different chemical linkages, either by benzene or by pyridine rings. We find the polyimide multilayers to be stable and with varying electronic properties. The finite band gap exhibited by every structure (monolayer and stacked) was sensitive to atomic arrangement. Stacking introduces dispersion to an otherwise flat band structure of the materials, which appeared to be highly sensitive to stacking direction. The effect of stacking was similar for each COF, but the magnitude of band structure change was different and dependent on the symmetry of the building blocks.

Reduction of Structural Defects in the GaSb Buffer Layer on (001) GaP/Si for High Performance InGaSb/GaSb Quantum Well Light-Emitting Diodes.

Monolithic integration of GaSb-based optoelectronic devices on Si is a promising approach for achieving a low-cost, compact, and scalable infrared photonics platform. While tremendous efforts have been put into reducing dislocation densities by using various defect filter layers, exploring other types of extended crystal defects that can exist on GaSb/Si buffers has largely been neglected. Here, we show that GaSb growth on Si generates a high density of micro-twin (MT) defects as well as threading dislocations (TDs) to accommodate the extremely large misfit between GaSb and Si. We found that a 250 nm AlSb single insertion layer is more effective than AlSb/GaSb strained superlattices in reducing both types of defects, resulting in a 4× and 13× reduction in TD density and MT density, respectively, compared with a reference sample with no defect filter layer. InGaSb quantum well light-emitting diodes were grown on the GaSb/Si templates, and the effect of TD density and MT density on their performance was studied. This work shows the importance of using appropriate defect filter layers for high performance GaSb-based optoelectronic devices on standard on-axis (001) Si via direct epitaxial growth.

On-chip silicon electro-optical modulator with ultra-high extinction ratio for fiber-optic distributed acoustic sensing

Ultra-high extinction ratio (ER) optical modulation is crucial for achieving high-performance fiber-optic distributed acoustic sensing (DAS) for various applications. Bulky acousto-optical modulators (AOM) as one of the key devices in DAS have been used for many years, but their relatively large volume and high power consumption are becoming the bottlenecks to hinder the development of ultra-compact and energy-efficient DAS systems that are highly demanded in practice. Here, an on-chip silicon electro-optical modulator (EOM) based on multiple coupled microrings is demonstrated with ultra-high ER of up to 68 dB while the device size and power consumption are only 260 × 185 μm2 and 3.6 mW, respectively, which are at least two orders of magnitude lower than those of a typical AOM. Such an on-chip EOM is successfully applied to DAS with an ultra-high sensitivity of −71.2 dB rad2/Hz (4 pε/√Hz) and a low spatial crosstalk noise of −68.1 dB rad2/Hz, which are very similar to those using an AOM. This work may pave the way for realization of next-generation ultra-compact DAS systems by integration of on-chip opto-electronic devices and modules with the capability of mass-production.

Growth modes and chemical-phase separation in GaP1−xNx layers grown by chemical beam epitaxy on GaP/Si(001)

We investigated the chemical beam epitaxy of GaP1−xNx grown on nominally (001)-oriented Si substrates, as desired for the lattice-matched integration of optoelectronic devices with the standard Si technology. The growth mode and the chemical, morphological, and structural properties of samples prepared using different growth temperatures and N precursor fluxes were analyzed by several techniques. Our results show that, up to x≈0.04, it is possible to synthesize smooth and chemically homogeneous GaP1−xNx layers with a high structural quality. As the flux of the N precursor is increased at a given temperature to enhance N incorporation, the quality of the layers degrades upon exceeding a temperature-dependent threshold; above this threshold, the growing layer experiences a growth mode transition from 2D to 3D after reaching a critical thickness of a few nm. Following that transition, the morphology and the chemical composition become modulated along the [110] direction with a period of several tens of nm. The surface morphology is then characterized by the formation of {113}-faceted wires, while the N concentration is enhanced at the troughs formed in between adjacent (113) and (1¯1¯3). On the basis of this study, we conclude on the feasibility of fabricating homogeneous thick GaP1−xNx layers lattice matched to Si (x=0.021) or even with N content up to x=0.04. The possibility of exceeding a N mole fraction of 0.04 without inducing coupled morphological–compositional modulations has also been demonstrated when the layer thickness is kept below the critical value for the 2D–3D growth mode transition.