Trilayer Devices Research Articles

All-solution-processed ultraflexible wearable sensor enabled with universal trilayer structure for organic optoelectronic devices.

All-solution-processed organic optoelectronic devices can enable the large-scale manufacture of ultrathin wearable electronics with integrated diverse functions. However, the complex multilayer-stacking device structure of organic optoelectronics poses challenges for scalable production. Here, we establish all-solution processes to fabricate a wearable, self-powered photoplethysmogram (PPG) sensor. We achieve comparable performance and improved stability compared to complex reference devices with evaporated electrodes by using a trilayer device structure applicable to organic photovoltaics, photodetectors, and light-emitting diodes. The PPG sensor array based on all-solution-processed organic light-emitting diodes and photodetectors can be fabricated on a large-area ultrathin substrate to achieve long storage stability. We integrate it with a large-area, all-solution-processed organic solar module to realize a self-powered health monitoring system. We fabricate high-throughput wearable electronic devices with complex functions on large-area ultrathin substrates based on organic optoelectronics. Our findings can advance the high-throughput manufacture of ultrathin electronic devices integrating complex functions.

Extremely large area (88 mm × 88 mm) superconducting integrated circuit (ELASIC)

Superconducting integrated circuit is a promising “beyond-CMOS” device technology enables speed-of-light, nearly lossless communications to advance cryogenic (4 K or lower) computing. However, the lack of large-area superconducting IC has hindered the development of scalable practical systems. Herein, we describe a novel approach to interconnect 16 high-resolution deep UV (DUV EX4, 248 nm lithography) full reticle circuits to fabricate an extremely large (88 mm × 88 mm) area superconducting integrated circuit (ELASIC). The fabrication process starts by interconnecting four high-resolution DUV EX4 (22 mm × 22 mm) full reticles using a single large-field (44 mm × 44 mm) I-line (365 nm lithography) reticle, followed by I-line reticle stitching at the boundaries of 44 mm × 44 mm fields to fabricate the complete ELASIC field (88 mm × 88 mm). The ELASIC demonstrated a 2X–12X reduction in circuit features and maintained high-stitched line superconducting critical currents. We examined quantum flux parametron circuits to demonstrate the viability of common active components used for data buffering and transmission. Considering that no stitching requirement for high-resolution EX4 DUV reticles is employed, the present fabrication process has the potential to advance the scaling of superconducting qubits and other tri-layer junction-based devices.

Spin blocking effect at Ni/Pt heterojunction

Spin current, the flow of spin angular momentum, can carry and transport energy and/or information without generating Joule heating, which makes spin-based devices become one of the potential aspects for the next-generation information processing devices. It is important to investigate the generation, transport, and detection of spins for developing spin-based devices, in which the spin transport and its related phenomena attract ongoing interest due to the complex interactions between spins and condensed matter system. Here, spin transport phenomenon is studied at a heterojunction consisting of ferromagnetic metal nickel and nonmagnetic heavy metal platinum, where transport spins are found to be totally blocked. Two series of spin-pumping devices, i.e. the yttrium iron garnet (YIG)/Ni/Pt trilayer devices and the contrastive YIG/Ni bilayer devices, are made in this work. The YIG serves as a substrate and spin-pump layer, on which nickel film and platinum film are deposited by a dc magnetron sputtering system. Spin currents are generated from YIG and injected into nickel layers by spin pumping technology. The voltage signals corresponding to the inverse spin Hall effect are detected and analyzed comparatively for both YIG/Ni/Pt trilayer device and YIG/Ni bilayer device. It is found that the platinum layers in YIG/Ni/Pt trilayer devices act only as charge current shunting but do not contribute to the spin-charge conversion. This implies that the spin current cannot transport through the Ni/Pt interface even when the nickel layer is as thin as 1 nm, in other words, the spin current is blocked at the Ni/Pt interface. Our result proposes a heterojunction that can block transport spins totally, which has never been discussed before, and the present study may expand the views and promote the development of spin-based devices.

Enhancement of Resistive Switching Performance in Hafnium Oxide (HfO2) Devices via Sol-Gel Method Stacking Tri-Layer HfO2/Al-ZnO/HfO2 Structures.

Resistive random-access memory (RRAM) is a promising candidate for next-generation non-volatile memory. However, due to the random formation and rupture of conductive filaments, RRMS still has disadvantages, such as small storage windows and poor stability. Therefore, the performance of RRAM can be improved by optimizing the formation and rupture of conductive filaments. In this study, a hafnium oxide-/aluminum-doped zinc oxide/hafnium oxide (HfO2/Al-ZnO/HfO2) tri-layer structure device was prepared using the sol-gel method. The oxygen-rich vacancy Al-ZnO layer was inserted into the HfO2 layers. The device had excellent RS properties, such as an excellent switch ratio of 104, retention of 104 s, and multi-level storage capability of six resistance states (one low-resistance state and five high-resistance states) and four resistance states (three low-resistance states and one high-resistance state) which were obtained by controlling stop voltage and compliance current, respectively. Mechanism analysis revealed that the device is dominated by ohmic conduction and space-charge-limited current (SCLC). We believe that the oxygen-rich vacancy concentration of the Al-ZnO insertion layer can improve the formation and rupture behaviors of conductive filaments, thereby enhancing the resistive switching (RS) performance of the device.

High-Efficiency Semitransparent Organic Photovoltaics Containing Vertical Multiheterojunctions

Although semitransparent organic photovoltaics (ST-OPVs) are attractive components of various building-integrated photovoltaic applications, there is an intrinsic trade-off in their power conversion efficiencies (PCEs) and average visible transmissions (AVTs)─because the photocurrent generated usually requires substantial absorption in the visible light that determines transmission. In this paper, we describe a vertically stacked tunable multiheterojunction strategy toward highly efficient ST-OPVs that simultaneously maintain high AVTs. The vertical triheterojunctions of the active layer comprise one polymer donor, D18, and two small molecule acceptors, Y1 and Y6, that were formed with a sequentially deposited (SD) method. The triheterojunction structures not only introduced cascading energy levels of their lowest unoccupied molecular energy levels that aligned in parallel to the charge extraction direction but also can be tuned by varying their relative thicknesses, thereby significantly improving charge transport in the ST-OPVs without severely suffering AVT losses. We demonstrate the universality and broad tunability of this technique for balancing the PCEs and AVTs of the devices. Our ST-OPVs achieved champion PCEs as high as 13.9% at an AVT of 22.8% (100 nm active layer with deposited trilayers having D18, Y1, and Y6 at 45, 5, and 50 nm, respectively) and 13.5% at an AVT of 23.8% (100 nm active layer with deposited trilayers having D18, Y1, and Y6 at 40, 10, and 50 nm, respectively), while the PCE of the device with a bulk heterojunction (BHJ) D18/Y6 (1:1 wt) active layer at 100 nm is 12.3% at an AVT of 17.0%. Relative to the conventional BHJ devices, the PCEs of the both types of SD trilayer devices increased by at least 10%, while the AVTs increased by at least 25%, indicating the effectiveness of the vertical multiheterojunction structures. These efficiencies of the SD trilayer devices are among one of the best records for such ST-OPVs at comparable AVTs.

Low-voltage, solution-processed, two-terminal organic bistable memory device

An low-voltage, solution-based spin cast-processed two-terminal bi-stable memory device was fabricated by using organic-inorganic-organic tri-layer structure (MEHPPV/ZnO/MEHPPV) onto indium tin oxide coated glass. Tri-layer device structure displayed the significant switching characteristics. The absence of degradation after 1 h retention test at 120 °C was noticed. The consistent memory behavior was noticed even after 50 cycles. Electron tunneling mechanism was utilized for describing switching mechanism of the device. The result emphasizes that the class of memory devices have been fabricated with organic-inorganic-organic nanocomposites, which has led to considerable research and development efforts to the scene of latent applications.

Improved artificial synapse performance of Pt/HfO2/BiFeO3/HfO2/TiN memristor through N2 annealing

A high-performance synaptic plasticity memristor based on Pt/HfO2/BiFeO3/HfO2/TiN structure was developed by magnetron sputtering technology, and the effects of N2 annealing treatment on its resistance and synaptic bionic properties were studied. The results show that with the N2 post annealing process, the memristor can exhibits excellent switching windows, outstanding uniformity and high durability. An improvement of ON/OFF resistance ratio of at least two orders of magnitude is achieved, and the pulse endurance can remain stable up to 106 s. Moreover, the basic synaptic biomimetic function is realized due to its excellent multi-level storage properties, and the conductivity of the memristor is modulated by multilayer perception (MLP) algorithm to simulate handwritten digital image recognition. Overall, its linearity and stability of the artificial synapse in the regulation process still have the space to be improved for the application, so it can be efficiently regulated by rapid thermal processing. It is convinced the tri-layer post-annealing HfO2-based devices hold the application potential of neuromorphic computing in the next generation memory devices.

Self-generated double transition-metal carbide MXene/Graphene oxide trilayered memristors for flexible electronics

Transition metal carbides (MXenes) proved to be promising two-dimensional (2D) material candidates that can overcome existing hurdles in flexible electronics. This study presents a comprehensive investigation of double transition metal (DTM) MXene Mo2TiC2Tx (as conducting top and bottom electrodes) and graphene oxide (GO as active layer) free-standing memristors fabricated under ambient conditions. Our free-standing trilayer devices retained both, primitive bipolar resistive switching and capacitive resistive switching characteristics in the same device that could be interconverted just by tuning the thickness of insulating GO layer. Furthermore, capacitive bipolar resistive switching phenomenon showed high durability (5000 cycles) and retention (105). Additionally, the increase in active layer thickness favored increase in internal self-generated electric field (capacitance) as well as the current on/off ratio of the device. Our DTM-MXenes based free-standing memristors exceptionally improved device performance that pave a pathway towards fabricating flexible self-generating data storage devices.

Fabrication and characterization of InSb nanosheet/hBN/graphite heterostructure devices

Semiconductor InSb nanosheet/hexagonal boron nitride (hBN)/graphite trilayers are fabricated, and single- and double-gate devices made from the trilayers are realized and characterized. The InSb nanosheets employed in the trilayer devices are epitaxially grown, free-standing, zincblende crystals and are in micrometer lateral sizes. The hBN and graphite flakes are obtained by exfoliation. Each trilayer is made by successively stacking an InSb nanosheet on an hBN flake and on a graphite flake using a home-made alignment stacking/transfer setup. The fabricated single- and double-gate devices are characterized by electrical and/or magnetotransport measurements. In all these devices, the graphite and hBN flakes are employed as the bottom gates and the gate dielectrics. The measurements of a fabricated single bottom-gate field-effect device show that the InSb nanosheet in the device has an electron field-effect mobility of ∼7300 cm2 V−1 s−1 and a low gate hysteresis of ∼0.05 V at 1.9 K. The measurements of a double-gate Hall-bar device show that both the top and the bottom gate exhibit strong capacitive couplings to the InSb nanosheet channel and can thus tune the nanosheet channel conduction effectively. The electron Hall mobility in the InSb nanosheet of the Hall-bar device is extracted to be larger than 1.1 × 104 cm2 V−1 s−1 at a sheet electron density of ∼6.1 × 1011 cm −2 and 1.9 K and, thus, the device exhibits well-defined Shubnikov–de Haas oscillations.

Josephson Effect in MgB2/Pd/Nb Trilayer Josephson Junctions

This paper reports fabrication techniques and results of MgB2/Pd/Nb trilayer Josephson junctions. The MgB2 bottom electrode was co-evaporated by molecular beam epitaxy (MBE) technique from both magnesium and boron sources at a low substrate temperature ~ 300 °C, while the interlayer and the top niobium electrode (Pd/Nb bilayer) were deposited ex-situ using RF sputtering. The junctions exhibited and Josephson effect as well as a modulation of the critical current in a magnetic field applied in a direction normal to the junction plane. Fractional and integer Shapiro steps were observed at voltages corresponding to the frequency of the applied microwave radiation field. The products of the junctions compare well with the previously reported values. The results suggest that it should be possible to fabricate all-MgB2 and MgB2 as one of the electrodes Superconductor/Normal/Superconductor (SNS), Superconductor/Insulator/Superconductor (SIS) or even Superconductor/Ferromagnet/Superconductor (SFS) tunnel junctions with interesting characteristics and for various applications.
 Keywords: MgB2; all-MgB2; Josephson Tunnel junctions; trilayer devices; Niobium

Maximized Hole Trapping in a Polystyrene Transistor Dielectric from a Highly Branched Iminobis(aminoarene) Side Chain.

We synthesized highly branched and electron-donating side chain subunits and attached them to polystyrene (PS) used as a dielectric layer in a pentacene field-effect transistor. The influence of these groups on dielectric function, charge retention, and threshold voltage shifts (ΔVth) depending on their positions in dielectric multilayers was determined. We compared the observations made on an N-perphenylated iminobisaniline side chain with those from the same side chains modified with ZnO nanoparticles and with an adduct formed from tetracyanoethylene (TCNE). We also synthesized an analogue in which six methoxy groups are present instead of two amine nitrogens. At 6 mol % side chain, hopping transport was sufficient to cause shorting of the gate, while at 2 mol %, charge trapping was observable as transistor threshold voltage shifts (ΔVth). We created three types of devices: with the substituted PS layer as single-layer dielectric, on top of a cross-linked PS layer but in contact with the pentacene (bilayers), and sandwiched between two PS layers in trilayers. Especially large bias stress effects and ΔVth, larger than those in the case of the hexamethoxy and previously studied dimethoxy analogues, were observed in the second case, and the effects increased with the increasing electron-donating properties of the modified side chains. The highest ΔVth was consistent with a majority of the side chains stabilizing the trapped charge. Trilayer devices showed decreased charge storage capability compared to previous work in which we used less donating side chains but in higher concentrations. The ZnO and TCNE modifications resulted in slightly more and less negative ΔVth, respectively, when the side chain polystyrene was not in contact with the pentacene and isolated from the gate electrode. The results indicate a likely maximum combination of molecular charge stabilizing activity and side chain concentration that still allows gate dielectric function.

Deep-blue high-efficiency triplet-triplet annihilation organic light-emitting diodes using donor- and acceptor-modified anthracene fluorescent emitters

Deep-blue organic electroluminescence (EL) emitters are important for full-color display and solid-state lighting applications of organic light-emitting diode (OLED) technology. Triplet-triplet annihilation (TTA) is one efficient approach for realizing efficient deep-blue EL. In this study, a PPI donor and a BI acceptor are connected via an anthracene (AN) bridge to obtain a bipolar deep-blue TTA emitter, PPI-AN-BI. The effects of the donor and the acceptor moieties are studied by comparing photophysical properties of molecules obtained by replacing either the PPI or the BI group with a phenyl (P) group to obtain BI-AN-P or PPI-AN-P. Non-doped OLEDs based on the three molecules display high-performance deep-blue EL. Using PPI-AN-BI as a non-doped emitter, a trilayer device exhibits a maximum external quantum efficiency (EQE) of 8.4% with a CIE index of (0.15, 0.15), and a bilayer device exhibits a maximum EQE of 6.9% with a CIE index of (0.15, 0.15). It is experimentally and theoretically demonstrated that triplet pair transition and enhanced oscillator strength can be the main reasons contributing to high performances. This work would provide an efficient method for designing deep-blue non-doped EL emitters.

Probe of antiferromagnetic transition via thermal-excited incoherent spin current

Spin Seebeck effect (SSE) for an yttrium iron garnet (YIG)/nickel oxide (NiO)/platinum (Pt) trilayer device was studied in a wide temperature range. It is found that the SSE signal is nonmonotonic in the temperature domain and shows a maximum around the Néel temperature of the NiO layer, which is similar to the temperature dependence of the spin pumping signal in the same device. This result identified that the thermal-excited incoherent spin currents are also sensitive to the fluctuation of an antiferromagnetic system and can be used to probe the antiferromagnetic phase transition. Furthermore, the antiferromagnetic NiO layer is considered to be valuable for the optimization of spin transport efficiency at YIG/Pt interface, which enhances the SSE signal around room temperature.

Improved Pulse-Controlled Conductance Adjustment in Trilayer Resistors by Suppressing Current Overshoot.

In this work, we demonstrate the enhanced synaptic behaviors in trilayer dielectrics (HfO2/Si3N4/SiO2) on highly doped n-type silicon substrate. First, the three dielectric layers were subjected to material and chemical analyses and thoroughly investigated via transmission electron microscopy and X-ray photoelectron spectroscopy. The resistive switching and synaptic behaviors were improved by inserting a Si3N4 layer between the HfO2 and SiO2 layers. The electric field within SiO2 was mitigated, thus reducing the current overshoot in the trilayer device. The reset current was considerably reduced in the trilayer device compared to the bilayer device without a Si3N4 layer. Moreover, the nonlinear characteristics in the low-resistance state are helpful for implementing high-density memory. The higher array size in the trilayer device was verified by cross-point array simulation. Finally, the multiple conductance adjustment was demonstrated in the trilayer device by controlling the gradual set and reset switching behavior.

Pyro-phototronic effect enhanced ZnO nanowire-based tri-layer heterojunction for visible light sensing and communication

Photodetector's performances can be effectively enhanced by utilizing the polarization charges generated at the local interface through the light-self-induced pyro-phototronic effect. In order to efficiently take advantage of the polarization charges of both polarities, here a tri-layer heterojunction consisting of one pyroelectric semiconductor ZnO nanowire and other two conventional semiconductors is prepared and its response characteristics to 648 nm laser illuminations are studied. The photocurrents at all the illuminant powers are significantly improved by the pyro-phototronic effect. At illuminant power of 0.04 mW, the responsivity is improved from 0.823 to 22.054 mA/W. Moreover, the effect of chopper frequency has been studied, showing that with the increase of chopper frequency, the photocurrent as well as responsivity first increases and then gradually saturates. Specifically, the responsivity at a chopper frequency of 400 Hz is nearly four times as large as that at 10 Hz, indicating possible applications in ultrafast pulsed light detection. In addition, the intermediate ZnO nanowire layer has been modulated to investigate its influence on the pyro-phototronic effect in this kind of tri-layer heterojunction devices. The results conclude that short ZnO nanowire layer is preferred as the intermediate layer for better pyro-phototronic effect improved device performances. At last, a visible light communication system using the tri-layer heterojunction device is demonstrated, successfully transmitting and decrypting the sent signal. This work provides deep understandings of the physical working mechanisms of the pyro-phototronic effect in tri-layer heterojunction devices, and also exhibits the huge potential of the tri-layer heterojunction devices in high performance photodetection and light communication. • ZnO nanowire based tri-layer heterojunction is demonstrated for enhancement of pyro-phototronic effect. • The intermediate ZnO layer's preference is short ZnO nanowires for optimizing the pyro-phototronic effect. • A visible light communication system is proposed for transmission and decryption of encrypted light input signal.

Tetramer of triphenylamine and similar derivatives with bromine atoms as hole injecting/transporting materials for efficient red phosphorescent OLEDs

Abstract Tetramer of triphenylamine and similar compounds having bromine atoms have been synthesized, characterized and tested as hole injecting/transporting layers of organic light-emitting diodes (OLEDs). Rather high glass transition temperatures of the derivatives were determined to be in a range of 99–163 °C. Some of the materials have suitable ionization potentials and adequate triplet state energies, which make them useful hole injecting/transporting layer materials for application in red phosphorescent devices. A simplified tri-layer device architectures of red OLEDs were prepared by adopting N-(1-diphenylamino[4,4′-biphenyl])-N,N-bis(4-bromophenyl)amine (1) or N,N-bis (1-diphenylamino[4,4′-biphenyl])-N-(4-bromophenyl)amine (2) as hole transporting layer (HTL) material. Tris(1-diphenylamino[4,4′-biphenyl])amine (3) was selected for the hole injecting layer (HIL) to combine with 1 or 2 to construct step-wise hole injection in the devices. Peak efficiencies of the device with a single 1-based HTL were 12.5%, 18.6 cd/A, and 13.1 lm/W, all of which were slightly lower than those of a step-wise device having an additional 3-based HIL (i.e. 14.0%, 22.8 cd/A, and 17.8 lm/W). Similarly, the device with 2-based HTL exhibited peak efficiencies up to 13.5%, 21.3 cd/A, and 17.6 lm/W; while those of the device with an additional 3-based HIL achieved higher values of 13.8%, 22.6 cd/A, and 18.4 lm/W. The results indicate a high potential of these newly synthesized hole injecting/transporting materials.

Anisotropic magnetoelectric functionality of ferromagnetic shape memory alloy heterostructures for MEMS magnetic sensors

In this report, the ferromagnetic shape memory alloy (Ni50Mn35In15) and Pb0.96La0.04Zr0.52Ti0.48O3 based bilayer (Ni-Mn-In/PLZT (260 nm/300 nm)), trilayer (Ni-Mn-In/PLZT/Ni-Mn-In (130 nm/300 nm/130 nm)) and four-layer (Ni-Mn-In/PLZT/Ni-Mn-In/PLZT (130 nm/150 nm/130 nm/150 nm)) multiferroic heterostructures with equal thickness ratios have been fabricated over Si substrates via DC/RF magnetron sputtering technique. The in-plane and out-of-plane magnetic hysteresis curves show the anisotropic nature of the ferromagnetic layer. The anisotropic magnetoelectric coupling characteristics have been investigated for all the fabricated devices by recording the induced magnetoelectric coupling voltages under both parallel and perpendicular applied magnetic fields to the plane of the device. Compared to all fabricated heterostructures, the trilayer structure exhibits the highest magnetoelectric coupling coefficients with 1.56 V/(cm Oe)-1 and 2.01 V/(cm Oe)-1 in longitudinal and transverse configurations, respectively. This anisotropic nature of magnetoelectric coupling can be used to measure the applied magnetic field direction. The rarely reported anisotropic AC magnetic field sensing parameters of the fabricated devices like Pearson’s r, sensitivity, and inaccuracy have been calculated. The trilayer device exhibits excellent AC magnetic field sensing parameters with inaccuracy, sensitivity, and linearity of 1.856% full-scale output (FSO), 0.63 mV cm−1 and 0.9993 in longitudinal configuration while 1.755% FSO, 1.18 mV Oe−1, and 0.9993 in the transverse configuration, respectively. Such nanoscale ferromagnetic shape memory alloys based symmetric multilayered multiferroic heterostructures pave the way for the design and development of futuristic MEMS magnetoelectric magnetic field sensor to detect the magnetic field and its spatial orientation.

Revealing the flexoelectric‐like response of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) thin films

In the last decade, the polymeric poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) semiconductor has been widely studied for their electrical and electrochemical properties and used in various applications such as flexible and transparent electrodes, optoelectronics and thermoelectric devices. Here, we report the intrinsic electromechanical coupling in trilayered stainless steel/PEDOT:PSS/Aluminum composites. The PEDOT:PSS thin film integrated in the multi‐layer serves as the transduction material itself and yields a remarkable flexoelectric‐like response when the cantilever shaped‐ device assembly is subjected to beam bending. Two orders of magnitude larger flexoelectric coefficients (up to μ′12 = 6 μC/m) were obtained for semiconducting PEDOT:PSS thin films, in comparison with those measured for insulating polymers. Besides, it is observed that flexoelectric effect may be enhanced when the conductivity of the trilayer device increases to a certain extent, especially after a simple dilution treatment that induces partial removal of excess hydrophilic PSS. These first results may open a new avenue for simply preparing flexible and highly sensitive curvature sensors with single electroactive semiconducting polymer layer between metal electrodes.

All-solution-processed UV-IR broadband trilayer photodetectors with CsPbBr3 colloidal nanocrystals as carriers-extracting layer

Colloidal quantum dots (CQDs) are very promising nanomaterials for optoelectronics due to their tunable bandgap and quantum confinement effect. All-inorganic CsPbX3 (X = Br, Cl and I) perovskite nanocrystals (NCs) have attracted enormous interests owing to their promising and exciting applications in photovoltaic devices. In this paper, all-solution-processed UV-IR broadband trilayer photodetectors ITO/ZnO/PbS/CsPbBr3/Au and ITO/ZnO/CsPbBr3/PbS/Au with high performance were presented. The role of CsPbBr3 QDs layer as the carriers-extracting layer in the trilayer devices was discussed. As compared with bilayer device ITO/ZnO/PbS/Au, both the dark currents and photocurrents under illumination from trilayer photodetectors are enhanced, but the trilayer photodetector ITO/ZnO(80 nm)/PbS(150 nm)/CsPbBr3(50 nm)/Au showed a maximum specific detectivity (D*) of 8.3 × 1012 Jones with a responsivity (R) of 35 A W−1 under 1.6 mW cm−2 980 nm illumination. However, another trilayer photodetector ITO/ZnO(80 nm)/CsPbBr3(50 nm)/PbS(150 nm)/Au showed a maximum D* of 1.73 × 1012 Jones with a R of 5.31 A W−1 under 6.8 mW cm−2 405 nm illumination. Further, the underlying mechanism for the enhanced performance of trilayer photodetectors was discussed. Thus, this strategy of all-solution-processed heterojunction configuration paves a facile way for broadband photodetectors with high performance.

Crystalline dependence of spin transmission in Cr2O3 thin films

Spin transmission in Cr2O3 films of different crystalline textures is studied experimentally. With Y3Fe5O12/Cr2O3/Pt trilayer devices, a spin current is injected into Cr2O3 by spin pumping from Y3Fe5O12, and the spin transmission is monitored by the inverse spin Hall voltage (VISHE) in Pt. For (0001) plane textured Cr2O3 films, VISHE vanishes quickly below the Néel temperature. However, the VISHE shows a broad shoulder below the Néel temperature for (112‾0) and (112‾3) plane co-textured Cr2O3. Such a difference in the temperature dependence of Cr2O3 can be understood by the different Néel vector orientations with respect to the injected spin moment direction.