Responsivity Of Photodetector Research Articles

High Responsivity and Ultra-Low Detection Limits in Nonlinear a-Si:H p-i-n Photodiodes Enabled by Photogating

Photodetectors operating at the wavelength in the visible spectrum are key components in high-performance optoelectronic systems. In this work, massive nonlinearities in amorphous silicon p-i-n photodiodes enabled by the photogating are presented, resulting in responsivities up to 744 mA/W at blue wavelengths. The detectors exhibit significant responsivity gains at optical modulation frequencies exceeding MHz and a more than 60-fold enhanced spectral response compared to the non-gated state. The detection limits down to 10.4 nW/mm2 and mean signal-to-noise ratio enhancements of 8.5 dB are demonstrated by illuminating the sensor with an additional 6.6 µW/mm2 red wavelength. Electro-optical simulations verify photocarrier modulation due to defect-induced field screening to be the origin of such high responsivity gains. The experimental results validate the theory and enable the development of commercially viable and complementary metal oxide semiconductor (CMOS) compatible high responsivity photodetectors operating in the visible range for low-light level imaging and detection.

Efficient photonics beam forming system incorporating super structure fiber Bragg grating for application in Ku band

We propose and demonstrate a photonic true-time delay beamforming system for a 1 × 4 linear phased array antenna, operating in the Ku-band, based on superstructured fiber Bragg gratings (SFBGs) with linearly rising equivalent chirps. The proposed beam-forming network operates at 18 GHz frequency, which is theoretically analyzed and simplified by simulated results. The SFBG has a distinct number of gratings in each beamforming path, which provides a large and progressive phase delay. The advantage of the proposed technique can be found in terms of its wavelength tunable scheme making the system squint-free. The proposed architecture is a true time delay optical beam forming a network, which enables squint-free beam steering of radio frequency (RF) signals. In this study, a technique known as double sideband modulation of multiple wavelengths is utilized to investigate the reflection quality of SFBG at various chirp rates. Taking into account that each segment of FBG consists of 50, 60, 70, and 80 gratings and phase shift section samples of each segment, the overall length of the SFBGs is calculated to be 2 cm, 2.4 cm, 2.8 cm, 3.2 cm, respectively, are used for calculating group delay. An equation in a closed form representing the corresponding dispersion is derived. SFBG group delay response is analyzed theoretically with required simulation to investigate the reflectance characteristics. All simulation work for designing the beam forming system is done on Optisystem version 19 and designing of Super structure fiber Bragg grating Optigrating version 4.2. The optically process wavelengths are detected by high speed dedicated photo-detector (PD) and delay response is investigated through array factor of each antenna. Errors in the fabricated SFBGs' group delay responses are examined also.

High responsivity and multi-wavelength response photodetector based on single bandgap AlInN film by magnetron sputtering

The AlInN film with a band gap of 2.96 eV is prepared on glass by radio frequency magnetron sputtering. Photoluminescence spectra reveals that the emission band is originated from both the band-edge and some defect-related radiation. The interdigital AlInN photodetector based on metal−semiconductor−metal (MSM) structure exhibits photoresponse characteristics from ultraviolet to visible light. The defect energy level is responsible for the multi-wavelength response of the low-energy incident irradiation light. The photodetector exhibits the best performance under 660 nm illumination, with a responsivity of 102 A/W, an external quantum efficiency of 190% and a specific detectivity of 2.8 × 109 Jones. These three factors improve by 4–6 orders of magnitude compared to point electrodes. The AlInN MSM interdigital electrode structure provides a relatively promising candidate structure for achieving high-performance multi-wavelength photodetectors.

To improve device performance of self-driven heterojunction photodetectors by inserting a thin layer of silver nanoparticles into the electron-transporting layer

Lead selenide colloidal quantum dots (CQDs) are widely used in infrared photodetectors due to their size-dependent bandgap tunability, facile solution-processing techniques and low cost. Heterojunctions (HJs) are usually used to construct device to facilitate the separation of excitons and the transportation of photogenerated carriers. Based on the solution-processed HJ photodetector ITO/ZnO/PbSe/Ag, in which PbSe CQDs layer acts as the active layer and ZnO nanoparticles (NPs) layer as the electron-transporting layer, a greatly enhanced-performance was obtained after inserting 10 nm Ag NPs layer within the ZnO NPs layer close to the HJ ZnO/PbSe interface. By optimizing the concentration of Ag NPs solutions and the location of Ag NPs thin layer in ZnO film, the maximum responsivity of the self-driven HJ photodetector ITO/ZnO(50 nm):Ag-NPs(10 nm):ZnO(50 nm)/PbSe(300 nm)/Ag reaches to 6.25 mA/W with a specific detectivity D* of 5.17 ×1011 Jones under 8.5 μW/cm² 1550 nm illumination at zero bias. Further, the underlain physical mechanisms for the enhanced-performance were discussed in details. In this way, it provides a very efficient method for enhanced-performance self-driven HJ photodetectors by inserting a thin layer of metal NPs into the electron-transporting layer close to the heterojunction interface.

The Influence of Surface Processing on the Surface Plasmonic Enhancement of an Al-Nanoparticles-Enhanced ZnO UV Photodectector.

Surface Plasmonic Resonance (SPR) induced by metallic nanoparticles can be exploited to enhance the response of photodetectors (PD) to a large degree. Since the interface between metallic nanoparticles and semiconductors plays an important role in SPR, the magnitude of the enhancement is highly dependent on the morphology and roughness of the surface where the nanoparticles are distributed. In this work, we used mechanical polishing to produce different surface roughnesses for the ZnO film. Then, we exploited sputtering to fabricate Al nanoparticles on the ZnO film. The size and spacing of the Al nanoparticles were adjusted by sputtering power and time. Finally, we made a comparison among the PD with surface processing only, the Al-nanoparticles-enhanced PD, and the Al-nanoparticles-enhanced PD with surface processing. The results showed that increasing the surface roughness could enhance the photo response due to the augmentation of light scattering. More interestingly, the SPR induced by the Al nanoparticles could be strengthened by increasing the roughness. The responsivity could be enlarged by three orders of magnitude after we introduced surface roughness to boost the SPR. This work revealed the mechanism behind how surface roughness influences SPR enhancement. This provides new means for improving the photo responses of SPR-enhanced photodetectors.

W18O49 Nanowire Arrays for Plasmonic Photodetector with Electromediated Broadband Photoresponse

Plasmonic semiconductors offer significant advantages for the development of photodetectors with a tunable wide spectral response. Herein, we developed a plasmonic semiconductor photodetector based on the W18O49 nanowire array (NWA) to achieve a tunable broadband photodetector by adjusting the plasmonic absorption intensity of the W18O49 NWA. The plasmonic absorption intensity could be mediated through adjusting the free electron density of the W18O49 NWA by applying the external voltage on the W18O49 NWA-loaded electrode in HCl electrolyte. When the applied voltage decreased from +2 to −2 V, the plasmonic absorption intensity of the W18O49 NWA gradually enhanced due to the increased electron density. As a result, the responsivity and detectivity of the W18O49 NWA-based photodetector in the visible–NIR region were dramatically increased. Especially, upon 940 nm illumination, the responsivity and detectivity could reach ∼47.2 mA W–1 and ∼8.22 × 109 Jones, respectively, which is much higher than the corresponding values (∼2.9 mA W–1 and ∼4.53 × 109 Jones) obtained by the W18O49 NWA-based photodetector with a low plasmonic absorption. This work proposes a promising strategy to construct broadband-tunable photodetectors by using low-cost nonmetallic plasmonic nanostructures.

CH3NH3PbI3/Au/Mg0.2Zn0.8O Heterojunction Self-Powered Photodetectors with Suppressed Dark Current and Enhanced Detectivity.

Interface engineering of the hole transport layer in CH3NH3PbI3 photodetectors has resulted in significantly increased carrier accumulation and dark current as well as energy band mismatch, thus achieving the goal of high-power conversion efficiency. However, the reported heterojunction perovskite photodetectors exhibit high dark currents and low responsivities. Herein, heterojunction self-powered photodetectors, composed of p-type CH3NH3PbI3 and n-type Mg0.2Zn0.8O, are prepared through the spin coating and magnetron sputtering. The obtained heterojunctions exhibit a high responsivity of 0.58 A/W, and the EQE of the CH3NH3PbI3/Au/Mg0.2Zn0.8O heterojunction self-powered photodetectors is 10.23 times that of the CH3NH3PbI3/Au photodetectors and 84.51 times that of the Mg0.2ZnO0.8/Au photodetectors. The built-in electric field of the p-n heterojunction significantly suppresses the dark current and improves the responsivity. Remarkably, in the self-supply voltage detection mode, the heterojunction achieves a high responsivity of up to 1.1 mA/W. The dark current of the CH3NH3PbI3/Au/Mg0.2Zn0.8O heterojunction self-powered photodetectors is less than 1.4 × 10-1 pA at 0 V, which is more than 10 times lower than that of the CH3NH3PbI3 photodetectors. The best value of the detectivity is as high as 4.7 × 1012 Jones. Furthermore, the heterojunction self-powered photodetectors exhibit a uniform photodetection response over a wide spectral range from 200 to 850 nm. This work provides guidance for achieving a low dark current and high detectivity for perovskite photodetectors.

Low-Cost and Simple Synthesis of Dispersed CsPbBr3 Perovskite Single-Crystal Wires with Lengths over 1 mm Using Bernoulli’s Principle

Compared with polycrystalline thin films, perovskite single crystals without grain boundaries have better photovoltaic performance and stability. However, due to the extremely low solubility of all-inorganic perovskite in organic solvents and the complex phase diagram of CsPbBr3, directly growing large-sized CsPbBr3 perovskite single-crystal wires is challenging. Here, we have developed an airflow-assisted growth method for the rapid synthesis of large quantities of high-quality, dispersed, ultralong CsPbBr3 single-crystal wires under ambient conditions. This method is green (no additives) and low cost (no special treatment). The growth kinetics of single-crystal wires using this method have been elucidated, and their structural and optoelectronic properties were characterized. Some of the CsPbBr3 single-crystal wires synthesized by this method can exceed 1 mm in length with a low trap density of about 9.06 × 1011 cm–3. The constructed photodetector responsivity is up to 0.365 A/W and detectivity is over 3.3 × 1013 Jones, indicating great potential for optoelectronic applications. This low-cost, high-quality all-inorganic CsPbBr3 single-crystal wire growth method is highly scalable and may facilitate the research and application of all-inorganic perovskite single crystals.

Metal–Semiconductor–Metal Ultraviolet Photodetectors Based on Al Nanoparticles in 4H-SiC Microholes

A significant ultraviolet (UV) detection enhancement is realized by etching microhole (MH) arrays and localized surface plasmon resonance (LSPR) of Al nanoparticles (NPs) on 4H-SiC metal–semiconductor–metal (MSM) photodetectors (PDs). 4H-SiC PDs with different diameters of MHs are fabricated, which exhibit an ultralow dark current of approximately 5.0 × 10–15 A at 5 V bias. The PD with 3 μm MH exhibits the best performance, and its peak responsivity is 35% higher than that of device without MH. The peak responsivity of PDs with both 3 μm MH and NPs enhanced nearly 6 times that without Al NPs. The PD with both 3 μm MH and Al NPs indicates the best detection performance, with a maximum detectivity of 4.0 × 1013 Jones at 270 nm, which is nearly an order of magnitude higher than devices without Al NPs. The fabricated MH and Al NPs MSM PDs have a high response on the order of nanoseconds, with a rise/decay time of 2.1 ns/2.5 ns at 5 V bias. The complementary optical properties of MH and Al NPs with 4H-SiC can promote the development and application of high-performance UV PDs.

Exfoliated Se nanoparticles decorated on MoS2/paper-based heterojunction as a flexible, self-powered and highly responsive photodetector

Self-powered heterostructure based photodetectors are of great research interest owing to their zero-power consumption, enhanced light-matter interaction, and the ability to respond in harsh environmental conditions. Selenium (Se) nanoparticles have been recently explored in photodetectors due to their high absorption coefficient and superior light-sensing ability. However, most reported Selenium based photoconductors utilize sophisticated device fabrication methodology, requiring regulated environmental conditions, elevated temperature and face flexibility issues. This work demonstrates a discrete(localized) heterojunction of exfoliated Selenium decorated on hydrothermally grown MoS2/paper-based high-performance, flexible, and self-powered photodetector. X-ray Diffraction and Raman Spectroscopy studies reveal the presence of hexagonal Se and the SEM image shows the uniformly grown MoS2 on cellulose paper. It also confirms the presence of Se clustered nanoparticles. The hybrid heterostructure device displays broadband response in the Vis-NIR region. Upon light illumination, a built-in field is generated due to the efficient separation of the charge carriers, making the fabricated device to operate at zero bias. The as-fabricated device exhibits superior responsivity of 0.14 A/W and 0.49 A/W and detectivity of 4.55 × 1011 Jones (intensity- 35.8 mW/cm2) and 5.01 × 1010 Jones (intensity- 30.08 mW/cm2) upon Vis and NIR irradiation, respectively, at no bias. This superior performance is asserted to the peak absorption of Se nanoparticles in the NIR region. The device also showed superior resistance to bending stress and retained its original characteristics even after multiple bending cycles (∼1050). Hence, with this facile device fabrication and simple device architecture strategy, this work paves the way for developing high-performance tensile photodetectors.

Highly responsive self-driven broadband photodetector based on MoS2 nanorods/β-Ga2O3 heterojunction

Gallium oxide (Ga2O3) has drawn significant interest in developing high-performance deep-ultraviolet photodetector, but detection of broadband range from ultraviolet C to near-infrared remains a substantial challenge. The construction of heterojunction effectively broadens the spectral range for fabricating broadband photodetection devices with exciting optical and electrical properties. This work introduces a heterojunction comprised of horizontally aligned MoS2 nanorods on β-Ga2O3 nanogranules. The high-performing developed MoS2/β-Ga2O3 device operates in a self-driven mode in the broad spectral range from ultraviolet C -visible-near infrared (UVC-VIS-NIR). The device exhibits an ultralow dark current of 79 nA and a maximum responsivity of 94.92, 7.97, and 44.04 mAW−1 for UV (266 nm), Vis (625 nm), and NIR (950 nm) light illumination in self-driven conditions. Furthermore, the fabricated device shows the highest responsivity of 4.2 × 104 mAW−1, with a high external quantum efficiency of 1.97 × 104% and extremely low noise equivalent power of 4.03 × 10−14 WHz−1/2, under 266 nm light illumination at an applied bias of 5V. This study paves the way to develop MoS2/β-Ga2O3 based broadband photodetector for constructing high-performance self-driven optoelectronics devices with low power consumption.

A modified CVD method for the synthesis of monolayer MoS2 and photoelectric improvement by HfO2 passivation

Molybdenum disulfide (MoS2) is an emerging class of new materials with a wide range of potential practical applications. However, the uncontrollability of monolayer MoS2 synthesized by traditional chemical vapor deposition method and the low responsivity of MoS2 photodetectors limit its further development in the field of photoelectric detection. To achieve controlled growth of monolayer MoS2 and construct MoS2 photodetectors with a high responsivity, we propose a novel single crystal growth strategy of high-quality MoS2 by controlling the Mo to S vapor ratio near the substrate, and deposit a layer of hafnium oxide (HfO2) on the surface of MoS2 to enhance the performance of the pristine metal-semiconductor-metal structure photodetector. At a reverse bias of 8 V, the HfO2 passivated MoS2 photodetector features an extremely high responsivity of a response time of around 0.5 s, and a detectivity of Meanwhile, we deeply investigate the effect of the HfO2 layer on the performance of the fabricated MoS2 photodetector and propose a physical mechanism to interpret the obtained experiment results. These results might facilitate a better understanding on the performance modulation of the MoS2 photodetectors and accelerate the development of MoS2-based optoelectronic devices.

Molecular Synergistic Passivation for Efficient Perovskite Solar Cells and Self-Powered Photodetectors.

The interface between the perovskite and electron-transporting material is often treated for defect passivation to improve the photovoltaic performance of devices. A facile 4-Acetamidobenzoic acid (containing an acetamido, a carboxyl, and a benzene ring)-based molecular synergistic passivation (MSP) strategy is developed here to engineer the SnOx /perovskite interface, in which dense SnOx are prepared using an E-beam evaporation technology while the perovskite is deposited with vacuum flash evaporation deposition method. MSP engineering can synergistically passivate defects at the SnOx /perovskite interface by coordinating with Sn4+ and Pb2+ with functional group CO in the acetamido and carboxyl. The optimized solar cell devices can achieve the highest efficiency of 22.51% based on E-Beam deposited SnOx and 23.29% based on solution-processed SnO2 , respectively, accompanied by excellent stability exceeding 3000h. Further, the self-powered photodetectors exhibit a remarkably low dark current of 5.22×10-9 Acm-2 , a response of 0.53AW-1 at zero bias, a detection limit of 1.3×1013 Jones, and a linear dynamic range up to 80.4dB. This work proposes a molecular synergistic passivation strategy to enhance the efficiency and responsivity of solar cells and self-powered photodetectors.

Control over Charge Carrier Mobility in the Hole Transport Layer Enables Fast Colloidal Quantum Dot Infrared Photodetectors

Solution-processed colloidal quantum dots (CQDs) are promising materials for photodetectors operating in the short-wavelength infrared region (SWIR). Devices typically rely on CQD-based hole transport layers (HTL), such as CQDs treated using 1,2-ethanedithiol. Herein, we find that these HTL materials exhibit low carrier mobility, limiting the photodiode response speed. We develop instead inverted (p-i-n) SWIR photodetectors operating at 1370 nm, employing NiOx as the HTL, ultimately enabling 4× shorter fall times in photodiodes (∼800 ns for EDT and ∼200 ns for NiOx). Optoelectronic simulations reveal that the high carrier mobility of NiOx enhances the electric field in the active layer, decreasing the overall transport time and increasing photodetector response time.

Flexible metal/semiconductor/metal type photodetectors based on manganese doped ZnO nanorods

High-performance flexible photodetectors are one of the most interesting research areas due to their great possibilities for a variety of applications such as portable and wearable optoelectronics. This study verifies the performance of flexible metal/semiconductor/metal-type photodetector based on pristine and manganese doped ZnO nanorods (ZnO-NRs) prepared in two different concentrations of zinc precursors and manganese dopant at low temperatures. The photodetectors having ZnO-NRs with high aspect ratios were investigated by various material characterization techniques such as electron paramagnetic resonance and photoluminescence spectroscopy to confirm the relationship between defect concentrations and photodetector performance parameters. It has been calculated that the detectivity (D*) and responsivity (R) of the ZnO nanorod-based photodetectors increased 20 and 18 folds, respectively by increasing the concentration of zinc precursor. Besides the D* and R values of the photodetectors, prepared by the 16.5 mM zinc precursor, increased 18 and 4.5-fold, respectively, after manganese doping. We confirmed that even a very low concentration of zinc precursor could produce a photodetector with high performance in photo-response characteristics, flexibility, and stability against 10,000 cycles of convex/concave bending.

Improving the Performance of HPHT-Diamond Detectors for Pulsed X-Ray Dosimetry Using the Synchronous Detection Technique

A single-crystal diamond sample grown by high-pressure high-temperature (HPHT) technique was used for the fabrication of a metal–semiconductor–metal (MSM) photoconductor. The sample quality was evaluated by means of spectral photocurrent measurements highlighting the presence of a significant density of defect states within the diamond bandgap, responsible for trap-mediated conduction mechanisms. The photoconductor was fully characterized under 6 MeV pulsed X-rays, sourced by a medical linear accelerator (LINAC), in the 0.05–20 Gy and 0.017–0.100 Gy/s dose (D) and dose-rate (DR) ranges, respectively. Photocurrent measurements performed with a conventional precision electrometer showed that the detector performance is strongly affected by charge-trapping phenomena, resulting in a sublinear dependence with the DR (power-law dependence with an exponent of 0.86). Measurements were repeated in the same experimental conditions by coupling the detector to a specifically developed gated integrator, allowing for a synchronous integration of photocurrent pulses (limited to 40 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <inline-formula> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> </i> s) centered on each impinging X-ray pulse. In this case, the detector photoresponse showed an excellent linearity with both the D and the DR (power-law dependence with 1.0009 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.0004 and 1.009 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.005 exponents, respectively). Significantly, the proposed synchronous integration technique is then able to mitigate the detrimental effect that defects have on detector performance. The proposed method paves, therefore, the way to the exploitation of HPHT diamond as a low-cost alternative to single-crystal chemical vapor deposition (CVD)-diamond for the fabrication of accurate and linear X-ray dosimeters.

High-responsivity ultraviolet–visible photodetector based on an individual (GaN)1-x(ZnO)x solid solution nanobelt

(GaN)1-x(ZnO)x solid solution (SS) attracts much attention in the field of photodetectors and photocatalysis due to their excellent photoresponse and adjustable band gap. Although (GaN)1-x(ZnO)x nanoparticles, nanorods and nanosheets have been successfully synthesized, the preparation of one-dimensional (GaN)1-x(ZnO)x SS nanobelts (SSNBs) and their photoresponse performance are rarely reported due to the difficulty of preparation. In this study, single crystal (GaN)1-x(ZnO)x SSNBs with a ZnO content of ∼12.6% are synthesized by a convenient CVD method using liquid Ga as the nucleation site. The prepared NBs are pure (GaN)1-x(ZnO)x SS and not the two-phase compound of ZnO and GaN. More important, the SSNBs with tens of micrometers in length and hundreds of nanometers in width feature the excellent ultraviolet and visible light response. Upon UV illumination (365 nm), the photodetector based on a single (GaN)1-x(ZnO)x SSNB achieves a photoresponse speed of 330 ms and a photoresponsivity of 2.8 × 105 A/W. Under visible illumination (532 nm), the photodetector displays a photoresponse speed of 480 ms and a photoresponse of 1.9 × 104 A/W. This study not only proposes a new method for the synthesis of (GaN)1-x(ZnO)x SSNBs, but also paves the way for the use of (GaN)1-x(ZnO)x SSNBs as building blocks for broad-spectrum responsive photodetectors.

Ultra-high photo responsivity and self-powered photodetector in broad spectral range based on non-layered MnSe/WSe2 heterojunction

Due to its good p-type semiconductor characteristics, MnSe has a great application prospect in high-performance electronic and optoelectronic devices. However, heterojunctions of MnSe still need to be deeply studied to improve its electrical and photoelectric properties. Here, it is reported that the two-dimensional (2D) MnSe/WSe2 heterojunction is structured by the non-layered MnSe nanosheets synthesized by chemical vapor deposition (CVD) method and the mechanically exfoliated layered WSe2. The heterojunction device exhibits a rectification effect and a current on/off ratio of 6,557. Meanwhile, it has a broad spectral range response from ultraviolet (UV) to short-wave infrared radiation (SWIR) (300–2,200 nm), and achieves an ultra-high responsivity of 156 A/W, along with an excellent detectivity of 2.21 × 1012 jones, and an outstanding external quantum efficiency (EQE) of 36,400%. Moreover, the type II band alignment and the built-in potential in the MnSe/WSe2 heterojunction can facilitate the separation of the photoexcited electron-hole pairs, which enables the significant photovoltaic characteristics and self-powered photoswitching response. This work reveals the novel performance of the 2D MnSe/WSe2 heterojunction and a great potential in photoswitching, photodetector, and photovoltaic applications.

Long-wave bilayer graphene/HgCdTe based GBp type-II superlattice unipolar barrier infrared detector

Type-II superlattice (T2SL) material is used to design highly efficient next-generation infrared (IR) detectors. The flexibility of the material allows the integration of unipolar barrier IR detector architecture to suppress generation-recombination currents by blocking the majority charge carriers and improve device performance. This paper presents a self-powered T2SL unipolar barrier detector that operates in the long-wave IR regime. It comprises a contact layer made of p+-bilayer graphene (G) and a barrier layer made of p–-Hg1–xCdx=0.41Te (B) placed over a p+-Hg1–xCdx=0.2217Te absorber layer (p) and is known as the GBp detector. The optoelectronic characterization of the unipolar GBp detector is carried out using the Silvaco Atlas TCAD software. Under self-powered mode operation, the proposed GBp detector exhibits an improvement in photocurrent density of about 108 times. The dark current density of 0.4nA/cm2, the photocurrent responsivity of 7.82 A/W, the quantum efficiency of 91.44%, and the detectivity of 4.48 × 1014 cmHZ1/2/W are found at the liquid nitrogen temperature with a bias of –0.5 V. A dichroic ratio of 249 and a response time of less than 1 ps are likewise exhibited by the GBp detector. The substantial electric field at the contact/barrier heterointerface and the high barrier height in the conduction band, which result in an increased photodetection response, are attributed to this improved performance.

Monolithic Integrated Optical Receiver With a Metal Reflector-Assisted Surface Grating Coupler

High-speed optical receivers with high-efficiency power collection capability are highly demanded in an optical wireless communication system to achieve high sensitivity due to the power-limited eye safety regulation. A cascaded aperture optical receiver enabled by a waveguide photodetector and a grating coupler is a promising candidate because of its advantage of optimizing the electrical performance and the light collection independently. Here, we propose using a metal reflector (MR)-assisted grating coupler to increase the coupling efficiency further. A sensitivity-enhanced monolithic integrated optical receiver with an MR-assisted grating coupler is realized for the first time, which is demonstrated on the Indium Phosphide membrane on Silicon platform. The maximum −3 dB bandwidth and the external responsivity of the waveguide photodetector inside the proposed optical receiver are 52.2 GHz and 0.31 A/W, respectively. A back-to-back receiver sensitivity of −4.75 dBm for a 10 Gb/s OOK signal at the 7% FEC limit is achieved. With the enhancement of an MR, the achieved sensitivity is calculated to be 1.5 dB higher based on the measured results compared with the cascaded aperture optical receiver without an MR on the same platform.