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Preparation and characterization of carbon nanotubes by pulsed laser ablation in water for optoelectronic application
摘要： In the present work, preparation of multi-walled carbon nanotubes (MWCNTs) and carbon nanoparticles (CNPs) by using pulsed laser ablation of a graphite target in water without using catalyst was demonstrated. The effect of laser wavelength on the optical absorption and structural properties has been studied. X-ray diffraction (XRD) data shows the synthesized CNTs were polycrystalline and a peak related to the diamond structure was observed. Scanning electron microscope (SEM) investigation displays that the average diameter of CNTs synthesized with 532 nm was 20 nm and few micrometers in length, while the CNTs synthesized with 1064 nm have an average diameter of 75 nm and lengths of few sub-micrometers. Some of CNPs were noticed to deposit on the CNTs. Transmission electron microscope (TEM) was used to study the morphology of MWCNTs. Raman spectra confirm formation of MWCNTs during the presence of three peaks belonged to D-band, G-band and 2D-band. The intensity ratio of IG/ID is larger than unity for MWCTs prepared by two laser wavelengths. The colloidal MWCNTs prepared by 532 nm laser pulses showed higher absorption than that of MWCNTs prepared with 1064 nm. The current-voltage characteristics and responsivity of hybrid In/p-MWCNTs/n-Si heterojunction photodetectors prepared at different CNTs film thicknesses were investigated at room temperature. The responsivity of hybrid MWCNTs/n-Si photodetector has two peaks of response, the first peak was found at 650 nm and the second peak located at 850 nm. The maximum responsivity was 0.53 A/W at 532 nm was found for the photodetector fabricated with 532 nm laser. The energy band diagram of MWCNTs/Si heterojunction was constructed under illumination condition.
关键词： Hybrid photodetector,CNTs,Laser ablation,CNTs thickness,Laser wavelength
更新于2025-09-23 15:19:57
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High performance UV photodetector based on MoS2 layers grown by pulsed laser deposition technique
摘要： Highly efficient ultraviolet (UV) photodetector based on MoS2 layers has been fabricated using pulsed laser deposition (PLD) technique. Systematic layer dependent photoresponse studies have been performed from single layer to 10 layers of MoS2 by varying the laser pulses to see the effect of the number of layers on the photoelectrical measurements. Raman and Photoluminescence studies have been carried out to ensure the growth of high-quality MoS2 layers. Layers of MoS2 grown at 100 pulses were found to exhibit the characteristic Raman phonon modes i.e. E1 2g and A1g at 383.8 cm-1 and 405.1 cm-1 respectively and Photoluminescence (PL) spectra show B exciton peak for MoS2 at around 625 nm suggesting the growth of high-quality MoS2 layers. Atomic force microscopy (AFM) thickness profiling and cross sectional-high resolution transmission electron microscopy (HRTEM) analysis gives the thickness of grown MoS2 to be 2.074 nm and 1.94 nm, respectively, confirming the growth of trilayers of MoS2. X-ray photoelectron spectroscopy (XPS) spectra of the grown trilayer sample show characteristic peaks corresponding to Molybdenum and Sulphur doublet (Mo4+ 3d5/2,3/2 and S 2p3/2,1/2) confirming the chemical state of pure MoS2 phase without the presence of any Molybdenum oxide state. Dynamic photoelectrical studies with Indium Tin Oxide (ITO) as contact electrode upon UV laser illumination show superior responsivity of 3×104 A/W at 24 μW optical power of the incident laser (λ=365 nm) and very high detectivity of 1.81×1014 Jones at a low applied bias of 2 V. The obtained results are highly encouraging for the realization of low power consumption and highly efficient UV photodetectors based on MoS2 layers.
关键词： Pulsed laser deposition technique (PLD),2D material,UV photodetector,ITO electrode,cross-sectional TEM,Raman,MoS2 layers,XPS,AFM
更新于2025-09-23 15:19:57
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Chemical vapor deposition all-inorganic CsPbI <sub/>2</sub> Br perovskite nanofibers for photodetector
摘要： Chemical vapor deposition method can prepare perovskite films with controllable morphology and adjustable photoelectric properties. In this work, we have prepared CsPbI2Br films at 400 °C–700 °C using chemical vapor deposition method. The grain size of perovskite film increases with the deposition temperature increment because higher temperature provides greater driving force for nucleation expansion. CsPbI2Br film deposited at 600 °C shows nanofiber structure with polycrystalline property accompanied by local single crystal structure. Steady-state and time-resolved fluorescence measurement explored the charge carrier recombination process of perovskite films. The photodetector based on CsPbI2Br film deposited at 600 °C shows excellent photoelectric response and switching ratio characteristics. This is ascribed to low defect density and fast charge transport along 1D fiber channels.
关键词： photodetector,perovskite,chemical vapor deposition,nanofibers
更新于2025-09-23 15:19:57
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Carrier transport and recombination dynamics of InAs/GaAs sub-monolayer quantum dot near infrared photodetector
摘要： Here, we present a relative study of tunnel-induced photocarrier escape processes in a laterally coupled InAs sub-monolayer quantum dot-based photodetector (SML QD-PD) as a function of fractional coverage from 0.4 ML to 0.8 ML. Both by simulation and experiment, we have quantitatively described the temperature dependent interband photoresponse spectrally tuned in the near infrared region (835 nm–890 nm) on the basis of mutual competition between the interband carrier recombination and interdot tunneling lifetime with varying SML coverage. The progressively increasing recombination lifetime and decreasing interdot tunneling lifetime with increasing SML coverage has attributed to a faster photoresponse and greater responsivity. At higher coverage fraction, tunnel induced fast speed photocarrier transit through lateral array of SML QDs has been found to be capable of offering a faster temporal response (100 μs) with faithful reproducibility up to higher frequencies (1.3 KHz). Here, we report a powerful strategy to simultaneously tune responsivity, speed of time response and detectivity by externally controlling the SML coverage. This time response is measured to be nine times faster than a conventional SK QD photodetector. With increased coverage, inhibition of dark current due to trapping of injected charge carriers up to higher temperatures have resulted in high sustainable photodetectivity of 8 × 1011 cm Hz1/2 w?1 at ~250 K that offers near room temperature photodetection.
关键词： photoconductive gain,quantum dot photodetector,inter-dot tunneling,submonolayer coverage,near-infrared photoresponse,recombination dynamics,temporal photoresponse
更新于2025-09-23 15:19:57
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Polarization-Sensitive Self-Powered Type-II GeSe/MoS2 Van der Waals Heterojunction Photodetector
摘要： Polarization-sensitive photodetectors are highly desirable for high performance optical signal capture and stray light shielding in order to enhance the capability for detection and identification of targets in the dark, haze and other complex environments. Usually, filters and polarizers are utilized for conventional devices to achieve polarization-sensitive detection. Herein, to simplify the optical system, a 2-D self-powered polarization-sensitive photodetector is fabricated based on a stacked GeSe/MoS2 van der Waals (vdWs) heterojunction which facilitates efficient separation and transportation of the photogenerated carriers, due to type-II band alignment. Accordingly, a high performance self-powered photodetector is achieved with merits of a very large on-off ratio photocurrent at zero bias of currently 104 and a high responsivity (Rλ) of 105 mA/W with the external quantum efficiency (EQE) of 24.2%. Furthermore, a broad spectral photoresponse is extended from 380 nm to 1064 nm owing to the high absorption coefficient in a wide spectral region. One of the key benefits from these highly anisotropic orthorhombic structures of layered GeSe is self-powered polarization sensitive detection with a peak/valley ratio up to 2.95. This is realized irradiating with a 532 nm wavelength laser with which a maximum photoresponsivity of up to 590 mA/W is reached when the input polarization is parallel to the armchair direction. This work provides a facile route to fabricate self-powered polarization-sensitive photodetectors from GeSe/MoS2 vdW heterojunctions for integrated optoelectronic devices.
关键词： polarization sensitive photodetector,self-powered,type-II band alignment,GeSe/MoS2 heterojunction,broad spectral photoresponse
更新于2025-09-23 15:19:57
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Fabrication of rapid response self-powered photodetector using solution-processed triple cation lead-halide perovskite
摘要： Self-powered photodetectors (PDs) are suitable for application in smart systems, image sensing and optical communications. Herein, a self-powered PD based on triple cation lead-halide perovskite (TCLP) is reported. We showed the effect of bromide concentration on the optical and structural properties of the TCLP films. Additionally, an environmental stability test was conducted and it was found that TCLP with 10% Br can remain stable for up to 128 days after exposure to ambient air. Using this material, a self-powered perovskite PD was fabricated and demonstrated an impressive performance with a responsivity of 0.52 A W?1, detectivity of 8.8×1012 Jones, on/off ratio of 7.3×105, and a rapid rise and decay time of 19 μs and 21 μs, respectively. This work offers a useful insight into the effects the fabrication method of the thin film plays in building low-cost, stable, and high-performance self-powered PDs for application in structural health monitoring, imaging, optical communication, and biomedical sensing.
关键词： surface coverage,perovskite,self-powered,photodetector,triple cation
更新于2025-09-23 15:19:57
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High performance Zn-diffused planar mid-wavelength infrared type-II InAs/InAs <sub/>1a??x</sub> Sb <sub/>x</sub> superlattice photodetector by MOCVD
摘要： We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1?xSbx superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77 K, the photodetector exhibits a peak responsivity of 0.70 A/W at 3.65 μm, corresponding to a quantum efficiency of 24% at zero bias without anti-reflection coating, with a 50% cutoff wavelength of 4.28 μm. With an R0A value of 3.2 × 105 Ω cm2 and a dark current density of 9.6 × 10?8 A/cm2 under an applied bias of ?20 mV at 77 K, the photodetector exhibits a specific detectivity of 2.9 × 1012 cm Hz1/2/W. At 150 K, the photodetector exhibits a dark current density of 9.1 × 10?6 A/cm2 and a quantum efficiency of 25%, resulting in a detectivity of 3.4 × 1011 cm Hz1/2/W.
关键词： specific detectivity,metal-organic chemical vapor deposition,type-II InAs/InAs1?xSbx superlattices,quantum efficiency,Zn-diffused planar mid-wavelength infrared photodetector
更新于2025-09-23 15:19:57
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Fast-Response and Self-Powered Cu <sub/>2</sub> O/ZnO Nanorods Heterojunction UV-Visible (570 nm) Photodetectors
摘要： A fast, self-powered photodetector (PD) capable of UV to visible (570 nm) sensing based on the p-Cu2O/n-ZnO nanorods (NRs) heterostructure is reported. The PD shows a spectral response range from 380 nm to 570 nm, which is suitable for ambient light sensing applications. The PD exhibits good rectifying characteristics with a low leakage current and a low turn-on voltage of ～0.3 V. The responsivities of the self-powered PD are 0.24 A W?1 and 0.06 A W?1 at 380 and 450 nm, respectively. The rise/recovery time of the PD are 0.02/0.03 s and 0.01/0.02 s for UV (370 nm) and visible light (450 nm), respectively. Upon UV light illumination, the long, persistent photocurrent (or recovery time) caused by ZnO NRs can be eliminated using the self-powered mode.
关键词： fast-response,p-Cu2O/n-ZnO nanorods heterostructure,self-powered photodetector,UV-Visible sensing
更新于2025-09-23 15:19:57
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Enhance near infrared performance of n-type vertically aligned MoS <sub/>2</sub> flakes photodetector with active p-type CZTS electrodes
摘要： Recently, MoS2 is extensively investigated as a potential 2D material to develop ultra-high responsive photodetector (PD) due to its direct band gap and high optical absorption. However, the development of broadband PD is impede due to the low light absorption of MoS2 in NIR region. Metal-semiconductor-metal (MSM) photodetector with conventional metal electrode is being used as base device structure for MoS2 PD owing its simple and cost-effective structure. However, passive metal electrodes limit light absorption and diminish the performance of photodetector. Herein, a broadband, self-powered photodetector is developed with enhanced NIR response by using n-type vertical MoS2 flakes and p-type Cu2ZnSnS4 (CZTS) active electrodes. Owing to high absorption of p-type CZTS electrode in NIR region along with MoS2 flakes in visible region and formation of p-n junction at CZTS-MoS2 flakes interface shows ultra-high responsivity of 49.31 A W?1 and external quantum efficiency of 7.6×103 (%) with enhanced performance in NIR and visible region in contrast to conventional and passive metal electrode. Moreover, proposed device showed very high detectivity 3.4×1013(2.4×1013) in NIR (visible) region. The responsivity with active CZTS based electrodes is increased upto 11-times in comparison to passive gold electrodes in NIR region at 1100 nm. Photodetetcor with p-type CZTS electrodes shows long term stability and reproducibility over more than 4000 h which clearly revealed advantage of using p-type CZTS electrode for MoS2 based next generation photodetector applications.
关键词： photodetector,CVD,self-powered,MoS2 edge-enriched,Cu–Zn–Sn–S electrode,broadband
更新于2025-09-23 15:19:57
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Fabrication of AlN/GaN MSM photodetector with platinum as schottky contacts
摘要： The epitaxial aluminium nitride (AlN) layer was fabricated on a silicon (111) substrate by solid phase radio frequency (RF) MBE The samples morphological characteristic was successfully studied by ?eld emission SEM. Low photo-response of the hetero-structure layers is one of the main obstacles in order to fabricate a high performance of photodetector device. The platinum contacts on AlN/GaN metal-semiconductor-metal (MSM) photodetector were formed by RF sputtering machine. The conductivity behaviours, Schottky barrier height (SBH), photo-responses of the device were examined by source meter measurement. The SBH values of photo-device sensing were calculated as 0.488 eV and 0.479 eV for dark current and photo current, respectively. Good response times of the device were recorded as 21.48 ms and 12.69 ms for the bias voltage of 1 volt.
关键词： AlN,photodetector,aluminum nitride
更新于2025-09-23 15:19:57