Black Phosphorus Photodetector Research Articles

High-responsivity and high-speed black phosphorus photodetectors integrated with proton exchanged thin-film lithium niobate waveguides.

We present a high-performance broadband (450-1550 nm) black phosphorus photodetector based on a thin-film lithium niobate waveguide. The waveguides are fabricated by the proton exchange method with flat surfaces, which reduces the stress and deformation of two-dimensional materials. At a wavelength of 1550 nm, the photodetector simultaneously achieves a high responsivity and wide bandwidth, with a responsivity as high as 147 A/W (at an optical power of 17 nW), a 3-dB bandwidth of 0.86 GHz, and a detectivity of 3.04 × 1013 Jones. Our photodetector exhibits one of the highest responsivity values among 2D material-integrated waveguide photodetectors.

Black Phosphorus‐Based Absorbing Bionic Stacked Structured Linear Polarization Detector

AbstractPolarization detection technology is developing toward miniaturization and high integration from the early time‐division type, amplitude‐division type, aperture‐division type, etc., to a more integrated focal plane‐integrated array type. Focal plane detectors that rely on metal nanogrids are not able to guarantee both temporal and spatial resolution for lossless polarized light detection with a guaranteed level of integration. Inspired by Agabus japonicus, the black phosphorus (BP)‐based absorbing bionic stacked structured linear polarization detector (BSLD) is proposed. The BSLD exploits the polarization absorption properties of BP to achieve near‐lossless linear polarization detection. The design includes two orthogonally aligned polarization‐ and angle‐sensitive BP photodetectors. The detection performance of the detector is investigated and analyzed under a green laser beam (wavelength 532 nm). The BSLD designed in this paper can simultaneously measure the multi‐angle component information of the incident light at one point in space in order to resolve the polarization state of the incident light, providing a potential solution for an integrated, real‐time, and high‐resolution loss‐free polarization image sensor.

Silver-ion-passivated black phosphorus photodetectors to improve the response time

Black phosphorus following treatment with silver nitrate solution shows a remarkable improvement in the photoresponse time because Ag+ adsorption helps to reduce the defect concentration in it.

Waveguide integrated high-speed black phosphorus photodetector on a thin film lithium niobate platform

The thin film lithium niobate platform has shown its potential to support high-performance active and passive integrated photonic devices. Yet, due to the transparency of lithium niobate, it is not suitable for building a photodetector monolithically for conventional communication wavelengths. In this work, we demonstrate a high-speed photodetector on the thin film lithium niobate platform using hybrid integration of two-dimensional materials, i.e., black phosphorus. The black phosphorus and lithium niobate hybrid waveguide exhibit a high absorption coefficient of 1.56 dB/µm. The constructed metal-semiconductor-metal photodetector also presents a high responsivity of 2.64 A/W (at an input optical power of 25.1 µW). The 3-dB bandwidth of the device is as high as 1.97 GHz.

Resonant Grating-Enhanced Black Phosphorus Mid-Wave Infrared Photodetector.

Black phosphorus (BP) has emerged as a promising materials system for mid-wave infrared photodetection because of its moderate bandgap, high carrier mobility, substrate compatibility, and bandgap tunability. However, its uniquely tunable bandgap can only be taken advantage of with thin layer thicknesses, which ultimately limits the optical absorption of a BP photodetector. This work demonstrates an absorption-boosting resonant metal-insulator-metal (MIM) metasurface grating integrated with a thin-film BP photodetector. We designed and fabricated different MIM gratings and characterized their spectral properties. Then, we show that an MIM structure increased room temperature responsivity from 12 to 77 mA W-1 at 3.37 μm when integrated with a thin-film BP photodetector. Our results show that MIM structures simultaneously increase mid-wave infrared absorption and responsivity in a thin-film BP photodetector.

Ultra-sensitive polarization-resolved black phosphorus homojunction photodetector defined by ferroelectric domains

With the further miniaturization and integration of multi-dimensional optical information detection devices, polarization-sensitive photodetectors based on anisotropic low-dimension materials have attractive potential applications. However, the performance of these devices is restricted by intrinsic property of materials leading to a small polarization ratio of the detectors. Here, we construct a black phosphorus (BP) homojunction photodetector defined by ferroelectric domains with ultra-sensitive polarization photoresponse. With the modulation of ferroelectric field, the BP exhibits anisotropic dispersion changes, leading an increased photothermalelectric (PTE) current in the armchair (AC) direction. Moreover, the PN junction can promote the PTE current and accelerate carrier separation. As a result, the BP photodetector demonstrates an ultrahigh polarization ratio (PR) of 288 at 1450 nm incident light, a large photoresponsivity of 1.06 A/W, and a high detectivity of 1.27 × 1011 cmHz1/2W−1 at room temperature. This work reveals the great potential of BP in future polarized light detection.

Chip-integrated van der Waals PN heterojunction photodetector with low dark current and high responsivity

Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces. However, the reported chip-integrated two-dimensional material photodetectors were mainly implemented with the configuration of metal-semiconductor-metal, suffering from high dark currents and low responsivities at high operation speed. Here, we report a van der Waals PN heterojunction photodetector, composed of p-type black phosphorous and n-type molybdenum telluride, integrated on a silicon nitride waveguide. The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity. Under a bias of 1 V pointing from n-type molybdenum telluride to p-type black phosphorous, the dark current is lower than 7 nA, which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus photodetectors. An intrinsic responsivity up to 577 mA W−1 is obtained. Remarkably, the van der Waals PN heterojunction is tunable by the electrostatic doping to further engineer its rectification and improve the photodetection, enabling an increased responsivity of 709 mA W−1. Besides, the heterojunction photodetector exhibits a response bandwidth of ~1.0 GHz and a uniform photodetection over a wide spectral range, as experimentally measured from 1500 to 1630 nm. The demonstrated chip-integrated van der Waals PN heterojunction photodetector with low dark current, high responsivity and fast response has great potentials to develop high-performance on-chip photodetectors for various photonic integrated circuits based on silicon, lithium niobate, polymer, etc.

Lithography-free and high-efficiency preparation of black phosphorous devices by direct evaporation through shadow mask

Two-dimensional (2D) materials including black phosphorus (BP) have been extensively investigated because of their exotic physical properties and potential applications in nanoelectronics and optoelectronics. Fabricating BP based devices is challenging because BP is extremely sensitive to the external environment, especially to the chemical contamination during the lithography process. The direct evaporation through shadow mask technique is a clean method for lithography-free electrode patterning of 2D materials. Herein, we employ the lithography-free evaporation method for the construction of BP based field-effect transistors and photodetectors and systematically compare their performances with those of BP counterparts fabricated by conventional lithography and transfer electrode methods. The results show that BP devices fabricated by direct evaporation method possess higher mobility, faster response time, and smaller hysteresis than those prepared by the latter two methods. This can be attributed to the clean interface between BP and evaporated-electrodes as well as the lower Schottky barrier height of 20.2 meV, which is given by the temperature-dependent electrical results. Furthermore, the BP photodetectors exhibit a broad-spectrum response and polarization sensitivity. Our work elucidates a universal, low-cost and high-efficiency method to fabricate BP devices for optoelectronic applications.

High Photoresponse Black Phosphorus TFTs Capping with Transparent Hexagonal Boron Nitride.

Black phosphorus (BP), a single elemental two-dimensional (2D) material with a sizable band gap, meets several critical material requirements in the development of future nanoelectronic applications. This work reports the ambipolar characteristics of few-layer BP, induced using 2D transparent hexagonal boron nitride (h-BN) capping. The 2D h-BN capping have several advantages over conventional Al2O3 capping in flexible and transparent 2D device applications. The h-BN capping technique was used to achieve an electron mobility in the BP devices of 73 cm2V−1s−1, thereby demonstrating n-type behavior. The ambipolar BP devices exhibited ultrafast photodetector behavior with a very high photoresponsivity of 1980 mA/W over the ultraviolet (UV), visible, and infrared (IR) spectral ranges. The h-BN capping process offers a feasible approach to fabricating n-type behavior BP semiconductors and high photoresponse BP photodetectors.

Mid-infrared modulators integrating silicon and black phosphorus photonics

Vast applications of mid-infrared await the realisation of integrated photonic systems for this unique spectrum. Despite its potential as a universal platform for diverse active functions in mid-infrared, black phosphorus (BP) photonics still lacks integrated modulators for completion. Here we realize a hybrid integration of mid-infrared BP modulator on silicon photonics waveguide. Through gating effect, the anisotropic absorption in armchair BP can be tuned for enabling efficient optical modulation spanning ∼3.85–4.1 μm. The integrated waveguide design further promotes light–BP interaction that achieves a modulation depth of ∼5 dB at a low bias of −4 V. Additionally, the active footprint of 225 μm2 and the switching energy of ∼2.6 pJ are remarkably smaller compared to traditional counterparts. Function diversity of such a platform is further verified by integrating BP photodetector and modulator. The combination of two-dimensional materials and silicon photonics manifests a versatile platform to realise high-performance optoelectronic devices for compact on-chip mid-infrared system.

Black Phosphorus Photodetector Enhanced by a Planar Photonic Crystal Cavity

Black Phosphorus Photodetector Enhanced by a Planar Photonic Crystal Cavity

A wavelength-scale black phosphorus spectrometer

On-chip spectrometers with compact footprints are being extensively investigated owing to their promising future in critical applications such as sensing, surveillance and spectral imaging. Most existing miniaturized spectrometers use large arrays of photodetection elements to capture different spectral components of incident light, from which its spectrum is reconstructed. Here, we demonstrate a mid-infrared spectrometer in the 2–9 µm spectral range, utilizing a single tunable black phosphorus photodetector with an active area footprint of only 9 × 16 µm2, along with a unique spectral learning procedure. Such a single-detector spectrometer has a compact size at the scale of the operational wavelength. Leveraging the wavelength and bias-dependent responsivity matrix learned from the spectra of a tunable blackbody source, we reconstruct unknown spectra from their corresponding photoresponse vectors. Enabled by the strong Stark effect and the tunable light–matter interactions in black phosphorus, our single-detector spectrometer shows remarkable potential in the reconstruction of the spectra of both monochromatic and broadband light. Furthermore, its ultracompact structure that is free from bulky interferometers and gratings, together with its electrically reconfigurable nature, may open up pathways towards on-chip mid-infrared spectroscopy and spectral imaging. A single-photodetector spectrometer based on black phosphorus is demonstrated in the wavelength range from 2 to 9 μm. The footprint is 9 × 16 μm2. The spectrometer is free from bulky interferometers and gratings, and is electrically reconfigurable.

Rabi splitting obtained in a monolayer BP-plasmonic heterostructure at room temperature

Hybrid exciton states can be formed under the strong coupling of plasmons excited by metal nanostructures and excitons. Because of the large exciton binding energy, black phosphorus (BP) is an ideal platform to investigate the strong coupling. In this paper, we first demonstrate the strong coupling between local surface plasmon modes of different metal nanostructures and excitons in monolayer BP by adjusting the dimensions of nanostructures and polarization angle at room temperature. Moreover, the exciton dispersion curves obtained from the coupled oscillator model show the anti-crossing behavior at the exciton energy. And the Rabi splitting energies of the two different BP-metal nanostructures heterostructure are 250 meV and 202 meV, respectively, which paves a way towards the development of BP photodetectors, sensors, and emitters.

Cladded Surface-Plasmon-Enhanced BP Photodetector Based on the Damage-Free Metal-Semiconductor Interface

Surface plasmon is promising for applications in 2-D semiconductor photodetector due to their great potential to improve light absorption of 2-D semiconductor, where the poor light absorption of 2-D semiconductor limits the performance of 2-D photodetector to some extent. However, high-energy deposition processes of metal surface plasmon damage the surface crystal lattice of 2-D semiconductor, which hampers the current transport in 2-D semiconductor. Here, we report the cladded surface-plasmon-enhanced black-phosphorus (BP) photodetector with damage-free metal-semiconductor interface. Without the adverse effect of the direct deposition process for metal surface plasmon, the cladded surface-plasmon-enhanced BP photodetector exhibits a superior photoresponse enhancement by up to 1000%, which exceeds other conventional surface-plasmon-enhanced 2-D semiconductor photodetectors. Our results provide guidelines to design advanced surface-plasmon-enhanced 2-D semiconductor photodetector for practical application.

Spectral Responsivity and Photoconductive Gain in Thin Film Black Phosphorus Photodetectors

We have fabricated black phosphorus photodetectors and characterized their full spectral responsivity. These devices, which are effectively in the bulk thin film limit, show broadband responsivity ranging from <400 nm to the ~3.8 $\mu$m bandgap. In the visible, an intrinsic responsivity >7 A/W can be obtained due to internal gain mechanisms. By examining the full spectral response, we identify a sharp contrast between the visible and infrared behavior. In particular, the visible responsivity shows a large photoconductive gain and gate-voltge dependence, while the infrared responsivity is nearly independent of gate voltage and incident light intensity under most conditions. This is attributed to a contribution from the surface oxide. In addition, we find that the polarization anisotropy in responsivity along armchair and zigzag directions can be as large as 103 and extends from the band edge to 500 nm. The devices were fabricated in an inert atmosphere and encapsulated by Al$_2$O$_3$ providing stable operation for more than 6 months.

Black phosphorus photodetector integrated with Au nanoparticles

In this study, we propose a hybrid black phosphorus (BP)/Au nanoparticle (NP)-based photodetector, which greatly enhances the performance of photodetectors compared to BP-only photodetectors. By integrating Au NPs onto the BP surface, the light absorption was greatly enhanced owing to the localized surface plasmon resonance induced by the Au NPs, and the dark current of the photodetector was suppressed because the holes were withdrawn from the BP to the Au NPs due to the difference in the work function. After optimizing the density of the Au NPs, the responsivity of the BP/Au-NP photodetector reached 6000 and 500 A/W for 655 and 980 nm wavelengths, respectively, which are 60 and 500 times higher than those of BP photodetectors, respectively. The proposed hybrid photodetector, a two-dimensional (2D) semiconductor with noble metal NPs, opens up the possibility of realizing highly sensitive optoelectronic devices in the future.

Nanostructured multiple-layer black phosphorus photodetector based on localized surface plasmon resonance

In this paper, we propose a 20-layer black phosphorus (BP) photodetector based on a nanoscale plasmonic grating structure. Different grating materials are compared to optimize the absorption. The optical characteristics of the BP photodetector are thoroughly analyzed by absorption spectra, electric intensity distribution and power flow distribution. By introducing the nanoscale plasmonic grating, the enhanced absorption can be achieved up to 89.8% at the resonance wavelength of 714 nm for p-polarized light incidence. Besides, the cut-off wavelength of the 20-layer BP photodetector is extended to the middle infrared range with a high responsitivity of 60.94 A/W. Furthermore, the dark current was also calculated to demonstrate the electric properties of the BP photodetector, and the results reveal that our BP photodetector may allow for the development of the infrared photodetectors based on two-dimensional materials.

Cascade-type energy band design of a black phosphorus photodetector with high performance

A high performance hybrid black phosphorus/PbS QD photodetector with an additional junction through ligand-based energy band engineering.

Waveguide-Integrated Black Phosphorus Photodetector for Mid-Infrared Applications.

Midinfrared (MIR), which covers numerous molecular vibrational fingerprints, has attracted enormous research interest due to its promising potential for label-free and damage-free sensing. Despite intense development efforts, the realization of waveguide-integrated on-chip sensing system has seen very limited success to date. The huge lattice mismatch between silicon and the commonly used detection materials such as HgCdTe, III-V, or II-VI compounds has been the key bottleneck that hinders their integration. Here, we realize an integration of silicon-on-insulator (SOI) waveguides with black phosphorus (BP) photodetectors. When operating near BP's cutoff wavelength where absorption is weak, the light-BP interaction is enhanced by exploiting the optical confinement in the Si waveguide and grating structure to overcome the limitation of absorption length constrained by the BP thickness. Devices with different BP crystal orientation and thickness are compared in terms of their responsivity and noise equivalent power (NEP). Spectral photoresponse from 3.68 to 4.03 μm was investigated. Additionally, power-dependent responsivity and gate-tunable photocurrent were also studied. At a bias of 1 V, the BP photodetector achieved a responsivity of 23 A/W at 3.68 μm and 2 A/W at 4 μm and a NEP less than 1 nW/Hz1/2 at room temperature. The integration of passive Si photonics and active BP photodetector is envisaged to offer a potential pathway toward the realization of integrated on-chip systems for MIR sensing applications.

Black Phosphorus Infrared Photodetectors with Fast Response and High Photoresponsivity

Recently, black phosphorus (BP) has attracted enormous attention as the potential materials for next‐generation photonic device applications due to the high carrier mobility and the narrow bandgap. However, the metal–semiconductor–metal (MSM) structure of BP photodetectors cannot achieve simultaneously high photoresponsivity and fast photoresponse, due to its natural surface defects, the thinness of absorption layer, and the instability of BP in the air, which limits the application of BP MSM structure photodetectors. Here, infrared photodetectors with the multilayer BP sandwiched between the top protective layer of boron nitride and the bottom Au electrodes are demonstrated. The BP photodetectors exhibit a fast photoresponse of ≈16 µs, a broadband photodetection up to ≈2 µm, a high light on/off ratio of ≈103 which is higher than most BP photodetectors, together with an acceptable photoresponsivity of ≈1.55 A W−1 for the wavelength of 1550 nm at room temperature. Scanning photocurrent microscopy measurements show that the mechanism of BP photodetectors is a combination of photovoltaic effect and photoconductive effect. This work demonstrates an effective way to design high‐performance photovoltaic/photoconductive devices based on 2D materials.