Heterostructure Photodetector Research Articles

Blackbody‐Sensitive Uncooled Infrared Detector with Ultra‐Broadband and Ultrafast Photoresponse Based on Te/WTe2 Heterostructure

AbstractBlackbody‐sensitive uncooled infrared photodetectors with ultra‐broadband and ultrafast photoresponse have a profound impact on many areas of modern science and technology. However, it is a big challenge for both traditional photodetectors and emerging low‐dimensional ones to simultaneously have all the above characteristics. Here, this challenge is addressed by establishing a Te/WTe2 heterostructure photodetector. The built‐in field of the heterostructure and the crossing conduction and valence bands of WTe2 jointly result in a high responsivity and a visible‐to‐long‐wavelength‐infrared photoresponse range. The peak responsivity (at the 3.3 µm wavelength) reaches 914 mA W−1 at zero bias and 8.51 A W−1 at 2 V bias. Further, the joint action coupled with the high mobility of Te and WTe2 promotes the 3‐dB bandwidth to 153 kHz. The self‐powered blackbody responsivity and specific detectivity reach 235.7 mA W−1 and 1.1 × 108 cm Hz1/2 W−1, respectively. The former increases to 5.82 A W−1 at 1 V bias. Moreover, this device is polarization‐sensitive with a contrast ratio of 2. This work reveals the potential of the Te/WTe2 heterostructure for high‐performance room‐temperature infrared photodetectors.

Optically Active Defect Engineering via Plasma Treatment in a MIS‐Type 2D Heterostructure

AbstractAt the interface of 2D heterostructures, the presence of defects and their manipulation play a crucial role in the interfacial charge transfer behavior, further influencing the device functionality and performance. In this study, the impact of deliberately introduced photo‐active defects in the h‐BN layer on the interfacial charge transfer and photoresponse performance of a metal‐insulator‐semiconductor type heterostructure device is explored. The formation and concentration of defects are qualitatively controlled using an inductive coupled plasma treatment method, as evidenced by enhanced h‐BN defect emission and more efficient optically induced doping of graphene at the graphene/h‐BN interface. Besides, the use of the h‐BN layer between graphene and WS2 not only suppresses charge carriers in the dark state, but also promotes the separation of photo‐generated electron‐hole pairs and interfacial charge transfer due to the existence of defect levels, leading to orders of magnitude improvement in the light on/off ratio and self‐driving performance of the heterostructure photodetector. This strategy of controlling defect states in the insulating layer provides a new approach to optimize the charge transfer processes at the 2D interfaces, so as to expand its potential applications in the fields of electronic and optoelectronic devices.

Monolayer graphene/GaN heterostructure photodetector with UV-IR dual-wavelength photoresponses

An ultraviolet-infrared (UV-IR) dual-wavelength photodetector (PD) based on a monolayer (ML) graphene/GaN heterostructure has been successfully fabricated in this work. The ML graphene was synthesized by chemical vapor deposition (CVD) and subsequently transferred onto GaN substrate using polymethylmethacrylate (PMMA). The morphological and optical properties of the as-prepared graphene and GaN were presented. The fabricated PD based on the graphene/GaN heterostructure exhibited excellent rectify behavior by measuring the current–voltage (I–V) characteristics under dark conditions, and the spectral response demonstrated that the device revealed an UV-IR dual-wavelength photoresponse. In addition, the energy band structure and absorption properties of the ML graphene/GaN heterostructure were theoretically investigated based on density functional theory (DFT) to explore the underlying physical mechanism of the two-dimensional (2D)/three-dimensional (3D) hybrid heterostructure PD device. This work paves the way for the development of innovative GaN-based dual-wavelength optoelectronic devices, offering a potential strategy for future applications in the field of advanced photodetection technology.Graphical

Filter-Free UV Photodetectors Based on Unipolar Barrier Van der Waals α-In2Se3/h-BN Heterostructures.

Visible-blind ultraviolet (UV) light detection has a wide application range in scenes like space environment monitoring and medical imaging. To realize miniaturized UV detectors with high performance and high integration ability, new device structures without bulky light filters need to be developed based on advanced mechanisms. Here the unipolar barrier van der Waals heterostructure (UB-vdWH) photodetector is reported that realizes filter-free visible-blind UV detection with good stability, robustness, selectivity, and high detection performance. The UB-vdWH shows a responsivity of 2452AW-1, a photo on-off ratio of 2.94×105 and a detectivity of 1.26×1015Jones as a UV detector, owing to the intentionally designed barrier height that suppresses dark current and photoresponse to visible light during the transport process. The good performance remains intact during 104 test cycles or even under high temperatures, which proves the stability, and robustness of the UB-vdWH, thus shows the huge potential for a wider application range.

Wavelength-modulated polarity switch self-powered Bi2Se3/GaN heterostructure photodetector

Van der Waals and wide-bandgap materials-based heterostructures have garnered substantial attention in developing self-powered broadband photodetectors owing to their exceptional photovoltaic capabilities. These materials also hold great potential for breakthroughs in optoelectronics. However, limitations to low selectivity constrain the potential of heterostructures-based broadband detectors. Here, we design wavelength-selective polarity switching in a heterostructure photodetector consisting of bismuth selenide (Bi2Se3) and gallium nitride (GaN). The analysis revealed a positive photocurrent under ultraviolet-C illumination to visible wavelength, whereas a negative photocurrent under infrared wavelengths at zero applied bias. The exposure to distinct optical wavelengths leads to an inversion in the electric field polarity across the junction, resulting in polarity switching. The fabricated Bi2Se3/GaN self-powered ultra-broadband photonic device demonstrates a peak photoresponsivity of 584 mAW−1 (−297 mAW−1) at 355 nm (1405 nm) wavelength illumination and can detect weak signals up to 650 femto-watt. Our strategy revealed alternative avenues for developing polarity-switchable, self-powered ultra-broadband photodetectors, offering a first step towards creating wavelength-adaptable sensors for future applications.

Theoretical insights toward a highly responsive AgInSe2 photodetector

AbstractThis treatise showcases the design as well as modeling about a photodetector (PD) based on AgInSe2 (AISe), a direct bandgap chalcopyrite with a bandgap of 1.19 eV. The PD exhibits outstanding optical and electronic characteristics, showcasing remarkable performance. The PD has been systematically investigated by varying the width, carrier density, and defect densities of specific layers, as well as the interface defect density of specific interfaces. Various layers are optimized to enhance the overall performance of the PD and the impact of different device resistances is analyzed. The photocurrent (JSC) and voltage (VOC) of the heterostructure photodetector are determined to be 38.60 mA/cm2 and 1.0 V, in turn. The maximum responsivity (R) and detectivity (D*) are identified as 0.70 A/W and 4.60 × 1016 Jones, respectively at a wavelength of 940 nm. The spectral response exhibits significantly higher values in the range of 800–1000 nm, indicating the device's capability to detect near‐infrared (NIR) light. This research provides valuable insights for the manufacturing of AISe material‐based photodetectors with enhanced performance.

A theoretical analysis to reveal the prospects of MoS2 as a back surface field layer in TiS3-based near infrared photodetector

In this article, a photodetector based on TiS3 absorber material, featuring a narrow direct bandgap of 1 eV, has been simulated. Throughout this research, the J-V (current–voltage) curves and spectral responses have been explored by systematically varying the thickness, doping concentration, and defect density of specific layers. The JSC (short circuit current) and VOC (open circuit voltage) of the heterostructure photodetector are found to be 45.77 mA cm−2 and 0.693 V respectively. Also, the responsivity (R) and detectivity (D*) are 0.81 A W−1 and 2.19 × 1014 Jones at a light wavelength of 1100 nm. The spectral response exhibits significantly elevated values within the wavelength range of 800 nm to 1200 nm, indicating the device’s ability to detect light in the near-infrared (NIR) region effectively. The novel research offers valuable insights, emphasizing the material’s suitability for photodetector (PD) applications and signaling a promising direction for further research interest in photodetector development.

Efficient Carrier Multiplication in Self-Powered Near-Ultraviolet γ-InSe/Graphene Heterostructure Photodetector with External Quantum Efficiency Exceeding 161.

Carrier multiplication (CM) in semiconductors, the process of absorbing a single high-energy photon to form two or more electron-hole pairs, offers great potential for the high-response detection of high-energy photons in the ultraviolet spectrum. However, compared to two-dimensional semiconductors, conventional bulk semiconductors not only face integration and flexibility bottlenecks but also exhibit inferior CM performance. To attain efficient CM for ultraviolet detection, we designed a two-terminal photodetector featuring a unilateral Schottky junction based on a two-dimensional γ-InSe/graphene heterostructure. Benefiting from a strong built-in electric field, the photogenerated high-energy electrons in γ-InSe, an ideal ultraviolet light-absorbing layer, can efficiently transfer to graphene without cooling. It results in efficient CM within the graphene, yielding an ultrahigh responsivity of 468 mA/W and a record-high external quantum efficiency of 161.2% when it is exposed to 360 nm light at zero bias. This work provides valuable insights into developing next-generation ultraviolet photodetectors with high performance and low-power consumption.

Multilayer Graphene/Epitaxial Silicon Near‐Infrared Self‐Quenched Avalanche Photodetectors

Abstract2D materials and their heterostructures exhibit considerable potential in the development of avalanche photodetectors (APDs) with high gain, response, and signal‐to‐noise ratio. These materials hold promise in addressing inherent technical challenges associated with APDs, such as low light absorption coefficient, elevated noise current, and substantial power consumption due to high bias resulting in only moderate current gain. In this work, a macro‐assembled graphene nanofilm (nMAG)/epitaxial silicon (epi‐Si) vertical heterostructure photodetector with a responsivity of 0.38 A W−1 and a response time of 1.4 µs is reported. The photodetectors use high‐quality nMAG as the absorption layer and a lightly‐doped epi‐Si layer as the multiplication region under the avalanche mode to provide a high responsivity (2.51 mA W−1) and detectivity (2.67 × 109 Jones) at 1550 nm, which can achieve high‐resolution imaging. In addition, the APD displays a weak noise level and an avalanche gain of M = 1123. It can work with relatively low avalanche turn‐on voltages and achieve self‐quenching by switching from illumination to dark during avalanche multiplication, with a real‐time data transfer rate of 38 Mbps in near‐infrared light communication data links. The proposed structure enables the fabrication of high‐performance APDs in the infrared range using complementary‐metal‐oxide‐semiconductor (CMOS)‐compatible processes.

The GeSe/SnSe heterojunction photodetector with self-powered characteristics and high infrared response performance

We present a GeSe/SnSe van der Waals heterojunction fabricated using the wet transfer technique. GeSe and SnSe were synthesized via a low-temperature and atmospheric-pressure chemical vapor deposition method. The GeSe/SnSe heterostructure photodetector demonstrates remarkable rectification characteristics, boasting a rectification ratio of 102, along with an exceptionally low dark current, indicating minimal power consumption. Furthermore, it exhibits a broad optical response, spanning from the visible spectrum (450 nm) to the near-infrared (1064 nm). Under 808 nm laser illumination and reverse bias, the device achieves a responsivity of 19.82 A/W, a detectivity of 4.74 × 109 Jones, and an external quantum efficiency of 3048.32%. Notably, the GeSe/SnSe heterojunction photodetector also exhibits self-powered characteristics, with a responsivity of 0.11 mA/W and a detectivity of 5.44 × 106 Jones at zero bias voltage, accompanied by a fast response time of 23/61 ms (rise/fall). These findings underscore the effectiveness of the GeSe/SnSe heterojunction as a strategy for near-infrared photodetectors to simultaneously achieve low power consumption, high photoresponsivity, and self-powered photodetection, which is promising for optoelectronic device applications.

Group-IV based pin photodetectors for C-band application

GeSn photodetectors with Sn contents between 0% and 6.5% were grown pseudomorphically on Ge virtual substrates on Si by molecular beam epitaxy. Based on the similar functional dependence of the current-voltage characteristics, we conclude that a similar crystal defect is the cause of the recombination/generation centers in both the GeSn and the Ge reference sample. We found that dislocations are not the predominant recombination type. The signal-to-background ratio is a proper quantitative measure for the comparison of heterostructure photodetectors and with near zero bias operation in the C-band, the values of around 104 were obtained with 1 mW light input. For C-band operation, the optimal Sn contents are found to be between 2% and 4%.

High-Performance Broadband Image Sensing Photodetector Based on MnTe/WS2 van der Waals Epitaxial Heterostructures.

Two-dimensional transition metal dichalcogenide (TMDC) heterostructure is receiving considerable attention due to its novel electronic, optoelectronic, and spintronic devices with design-oriented and functional features. However, direct design and synthesis of high-quality TMDC/MnTe heterostructures remain difficult, which severely impede further investigations of semiconductor/magnetic semiconductor devices. Herein, the synthesis of high-quality vertically stacked WS2/MnTe heterostructures is realized via a two-step chemical vapor deposition method. Raman, photoluminescence, and scanning transmission electron microscopy characterizations reveal the high-quality and atomically sharp interfaces of the WS2/MnTe heterostructure. WS2/MnTe-based van der Waals field effect transistors demonstrate high rectification behavior with rectification ratio up to 106, as well as a typical p-n electrical transport characteristic. Notably, the fabricated WS2/MnTe photodetector exhibits sensitive and broadband photoresponse ranging from UV to NIR with a maximum responsivity of 1.2 × 103 A/W, a high external quantum efficiency of 2.7 × 105%, and fast photoresponse time of ∼50 ms. Moreover, WS2/MnTe heterostructure photodetectors possess a broadband image sensing capability at room temperature, suggesting potential applications in next-generation high-performance and broadband image sensing photodetectors.

Research of Photodetectors Based On Two-Dimensional Materials

With the discovery of graphene, people have discovered that two-dimensional materials have unique properties and significance. Therefore, two-dimensional material-based photodetectors are also very valuable for research. This article first discusses the excellent properties of photodetectors based on two-dimensional materials, including high sensitivity, high modulation frequency, and wide spectral response capability. Then, recent research results on two-dimensional SnSe2/GaP type-II heterostructure photodetectors and photodetectors utilizing two-dimensional WSe2 were introduced. Additional representative studies, including two-dimensional layered materials-based valanche photodetectors and two-dimensional tin (II) sulfide (SnS) nanoflakes-based photodetectors, were also shown. The prospects and challenges of photodetectors based on two-dimensional materials were also discussed at the end of the article. They can be applied in fields such as video imaging, gas sensing, biological imaging, safety, night vision, optical communication, and motion detection. The issues of device stability, mass production, cost, and uniformity need to be addressed and find their more ideal commercial applications.

Unveiling the potentiality of a self-powered CGT chalcopyrite-based photodetector: theoretical insights

The article demonstrates the design and modelling of CuGaTe2 direct bandgap (1.18 eV) chalcopyrite-based photodetector (PD), which has superb optical and electronic characteristics and shows remarkable performance on the photodetector. The photodetector has been investigated throughout the work by switching width, carrier and defect densities of particular layers and also the interface defect density of particular interfaces. The various layers have been optimized for the higher performance of the PD. Also, the impression of various device resistances has been analyzed. The JSC and VOC of the heterostructure photodetector is found to be 38.27 mA/cm2 and 0.94 V, in turn. The maximum responsivity, R and detectivity, D* are found to be 0.663A/W and 1.367 × 1016 Jones at a wavelength of 920 nm. The spectral response has a very high value in the range of 800 to 1000 nm light wavelength, which confirmed that this device is capable of detecting the near infrared (NIR) region of light. This work gives important guidance for the manufacture of CGT material-based photodetectors with higher performance.

Ideal Photodetector Based on WS2/CuInP2S6 Heterostructure by Combining Band Engineering and Ferroelectric Modulation.

Two-dimensional van der Waals (2D vdW) heterostructure photodetectors have garnered significant attention for their potential applications in next-generation optoelectronic systems. However, current 2D vdW photodetectors inevitably encounter compromises between responsivity, detectivity, and response time due to the absence of multilevel regulation for free and photoexcited carriers, thereby restricting their widespread applications. To address this challenge, we propose an efficient 2D WS2/CuInP2S6 vdW heterostructure photodetector by combining band engineering and ferroelectric modulation. In this device, the asymmetric conduction and valence band offsets effectively block the majority carriers (free electrons), while photoexcited holes are efficiently tunneled and rapidly collected by the bottom electrode. Additionally, the ferroelectric CuInP2S6 layer generates polarization states that reconfigure the built-in electric field, reducing dark current and facilitating the separation of photocarriers. Moreover, photoelectrons are trapped during long-distance lateral transport, resulting in a high photoconductivity gain. Consequently, the device achieves an impressive responsivity of 88 A W-1, an outstanding specific detectivity of 3.4 × 1013 Jones, and a fast response time of 37.6/371.3 μs. Moreover, the capability of high-resolution imaging under various wavelengths and fast optical communication has been successfully demonstrated using this device, highlighting its promising application prospects in future optoelectronic systems.

Polarization‐Sensitive and Self‐Driven Pyro‐Phototronic Photodetectors Based on MoS2‐Water Heterojunctions

AbstractPolarization‐sensitive and self‐driven pyroelectric‐based photodetectors have recently gained interest due to their potential application in artificial electronic eyes, biomedical imaging, and optical switches. Here, a photodetector based on light modulation‐induced polarization and depolarization of water molecules on the surface of a 2D MoS2 crystal is reported. The MoS2‐water heterostructure photodetector serves as a self‐driven pyro‐phototronic device that converts light‐induced thermal energy to electrical signals, leading to a transient photoresponsivity as high as 24.6 mA W−1 and a specific detectivity of 2.85 × 108 Jones under 470 nm wavelength at zero bias. Due to the formation of a built‐in electric field at the MoS2‐water interface, this structure also has a high steady–state responsivity of 3.62 A W−1 and detectivity of 9.18 × 108 Jones at 3 V bias, along with a fast response time of ≈0.74 ms. Moreover, due to the rearrangement of the hydrogen bond network in the liquid water upon visible light illumination, the MoS2‐water photodetector is light polarization‐sensitive. The simple fabrication process, low cost, polarization sensitivity, and high performance of the MoS2‐water structure make it an excellent candidate for liquid‐compatible photodetectors.

Er doped ZnO/SnS2/PEDOT:PSS Double Heterostructure Photodetector and its Application as Optocoupler

Er doped ZnO/SnS2/PEDOT:PSS Double Heterostructure Photodetector and its Application as Optocoupler

The effect of UVO treatment on TiO2-MAPbI3 heterostructure photodetector prepared in air atmosphere

TiO2-MAPbI3 heterostructure photodetectors were prepared in air atmosphere. The interface between electron transport layer and perovskite layer plays an important role in the performance of heterostructure photodetector. Here, ultraviolet ozone (UVO) treatment was used to improve the surface state of TiO2 film and the interfacial carrier transport performance of perovskite heterostructure photodetector. UVO treatment made TiO2 layer obtain the more oxygen vacancies and excess electrons, which were conducive to the electrical conductivity of electron transport layer. And MAPbI3 film deposited on UVO-treated TiO2 layer showed better uniformity and enhanced light absorption intensity due to the improved wettability of UVO-treated TiO2 film. Further research on photoelectric performance indicated that the increased light current and decreased dark current could be obtained for perovskite photodetector based on UVO-treated TiO2. In addition, the best exposure time was found to be 40 min. Compared with untreated sample, the detectivity of UVO-treated TiO2-MAPbI3 heterostructure photodetector increased by 80 %. Under 500 nm illumination with a light intensity of 1.6 mW cm−2 at −0.8 V bias, the responsivity, detectivity and external quantum efficiency of UVO-treated TiO2-MAPbI3 heterostructure photodetector reached 0.405 A W−1, 2.07 × 1011 Jones and 100.5 %, respectively.

Energy-Band Engineering By Remote Doping of Self-Assembled Monolayers Leads to High-Performance Igzo/P-Si Heterostructure Photodetectors

Advancements in emerging technologies, such as autonomous driving, artificial intelligence, medical imaging, and augmented reality, have increased the demand for high-resolution image sensors to transmit further accurate color information. To meet the performance requirements of these applications, several research have been accelerating towards the utilization of emerging low-dimensional semiconductor materials, such as metal oxides, transition metal dichalcogenides, perovskites, and other organic materials.Among them, metal oxide semiconductors (MOSs) are potential candidates for developing high-performance photodetectors. It can be synthesized over large areas using a simple/low-temperature process and are compatible with conventional fabrication equipment. However, MOS-based photodetectors still have several limitations, 1) the presence of charge traps and operational instability on the oxide surface, which degrade photodetection performance, and 2) the absence of an appropriate doping technique for MOS has blocked to improve photodetection performance via materials characteristic modification method.In this study, we present a strategy to overcome these limitations and significantly enhance the performance of IGZO, which is representative of oxide semiconductor thin film, based photodetector with high operation stability and sustainability under ambient atmospheres. We utilized energy-band engineering through an octadecylphosphonic acid (ODPA) self-assembled-monolayer (SAM)-based doping treatment to enhance the photoelectric characteristics of IGZO/p-Si hetero-interfaced devices (ISH). The ODPA consists of a head group of the hydroxyl group, which forms the self-assembled covalent bond formation of R–P–O–substrate. Combining the ODPA SAM with the oxide surface of IGZO provided carrier concentration control based on their a dipole effect, and remain the performance and functionality through the surface encapsulation. As a result, under a light-emitting diode (LED) wavelength with an intensity of 3.9 mW, the proposed device exhibited remarkable photo-switching current ratio of 4.33 × 103 A/A and negative differential resistance (NDR) phenomenon. Espacially, the dark current of the ODPA treated ISH is decreased about 10 times lower than as-fabricated ISH, which shows the possibility of signal noise minimization. These performance improvement is expected to be derived from band properties modulation through IGZO layer annealing and ODPA doping. To clarify the doping effect of each treatment, we characterized the ODPA self-assembled monolayer using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM) to provide comprehensive analysis of the heterointerface effects. We also characterized the electrical properties of IGZO thin-film transistors (TFTs) based on variations of the annealing temperature to clarify the ODPA doping effect.We evaluated 156 ODPA-treated IGZO/p-Si heterostructure photodetectors, which were scaled for fabrication on a 4 inch wafer. The devices exhibited a 100% yield, and uniform current behavior in the dark state (0.20 ± 0.06 nA) and light state (0.87 ± 0.15 µA), owing to an evenly deposited IGZO layer and a simple-to-treat ODPA doping scheme. Furthermore, consecutive sweeps of 20,000 cycles verified excellent cycle-to-cycle endurance, resulting in highly robust photoelectric behaviors without operational failure. Additionally, the performance of the ODPA-treated, IGZO/p-Si heterostructure photodetector remained unchanged for 237 days without degradation under atmospheric exposure (relative humidity (RH) = 37–53 % and 20.6–23.1 °C). Acknowledgements This research was supported by funding supports from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2020R1A2C1101647) and Korea government (MEST) (NRF-2017R1A2B3011222). Figure 1

SnS2/MoS2 van der Waals Heterostructure Photodetector with Ultrahigh Responsivity Realized by a Photogating Effect.

Photoresponsivity is a fundamental parameter used to quantify the ability of photoelectric conversion of a photodetector device. High-responsivity photodetectors are essential for numerous optoelectronic applications. Due to the strong light-matter interactions and the high carrier mobility, two-dimensional (2D) materials are promising candidates for the next-generation photodetectors. However, poor light absorption, lack of photoconductive gain, and the interfacial recombination lead to the relatively low responsivity of 2D photodetectors. The photogating effect, which extends the lifetime of photoexcited carriers, provides a simple approach to enhance responsivity in photodetector devices. Here, the O2 plasma treatment introduced surface traps on the SnS2 surface, leading to a gate-tunable photogating effect in SnS2/MoS2 heterojunctions. The heterojunction device exhibits an ultrahigh responsibility of up to 28 A/W. Moreover, the photodetector possesses a wide spectral photoresponse spanning from 300 to 1100 nm and a high specific detectivity (D*) of 4 × 1011 Jones under a 532 nm laser at VDS = 1 V. These results demonstrate that O2 plasma treatment is an efficient and simple avenue to achieve photogating effects, which can be employed to enhance the performance of van der Waals heterostructure photodetector devices and make them suitable for future integration into advanced electronic and optoelectronic systems.