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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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Ferroelectric ordering and energy storage capacity in lead-free Ba(Zr <sub/>0.2</sub> Ti <sub/>0.8</sub> )O <sub/>3</sub> nanoscale film capacitors fabricated using pulsed laser deposition technique
摘要： Dielectric thin film capacitors, storing large charge density, are useful in electric energy storing devices. Highly oriented lead-free BaZr0.20Ti0.80O3 (BZT20) thin films were grown on a conducting bottom layer La0.7Sr0.3MnO3 deposited on a MgO (100) substrate under an oxygen atmosphere using a pulsed laser deposition technique. X-ray diffraction studies indicate that BZT20 films were stabilized in a (100) oriented tetragonal phase. Microstructural studies on thin films indicate a smooth film (a roughness of ～1.25 nm) with a thickness of around 320 nm. The structural sensitive A1(TO2) Raman band exhibits a discontinuous change across the tetragonal-cubic phase transition temperature Tc ～ 275 K. The appearance of the broad Raman band in the cubic (Pm?3m) phase at an elevated temperature suggests the activation of symmetry forbidden Raman active bands. The temperature dependent band frequency and integrated intensity of the structural sensitive A1(TO2) band show anomaly across Tc. Temperature dependent dielectric studies (100–650 K) carried out in a wide range of frequencies 102–106 Hz on a fabricated Pt/BZT20/LSMO metal-insulator-metal capacitor suggest a broad dispersive peak of around 290 K. The polarization relaxation follows the Vogel-Fulcher relation with an activation energy of Ea = 0.047 eV and a freezing temperature of Tf = 246 K. The slim polarization P-E loops with a remanent polarization of ～89.6 μC/cm2 and an EC value of ～0.29 MV/cm were observed, suggesting its local ferroelectric ordering in corroboration with Raman and dielectric findings. From the P-E loop analysis, a large energy storage density of 31.9 J/cm3 and an energy storage efficiency of 56% were obtained. Our experimental results revealed that the BZT20 thin film capacitors have potential for energy storage device applications.
关键词： Ferroelectric ordering,Ba(Zr0.2Ti0.8)O3,energy storage capacity,nanoscale film capacitors,lead-free,pulsed laser deposition technique
更新于2025-09-16 10:30:52
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Influence of different post-annealing temperatures on physical properties of La0.72Ca0.28MnO3:Ag0.2 thin films by pulsed laser deposition technique
摘要： La0.72Ca0.28MnO3:Ag0.2/LaAlO3 (100) thin ?lms, prepared by pulsed laser deposition, were post-annealed at di?erent temperatures in air. X-ray di?raction technique were used to analysize the orientation and lattice parameter, atomic force microscope (AFM) and scanning electronic microscope (SEM) were employed to characterize the surface morphology of the thin ?lms. Resistance vs. temperature (R-T) behaviors of the thin ?lms were tested with standard four-probe technique. The surface morphology results show that the grain size increases and crystalline quality of the ?lms are improved with increased annealing temperature up to 1200 °C, while the amount of grains also increases; R-T results illustrate that both the temperature coe?cient of resistance (TCR) and metal-insulator transition temperature (TMI) of the ?lms, increase with annealing temperature. In particular, TCR of thin ?lm (post-annealing at 1200 °C) reaches 28.8%·K?1, which makes such ?lms be promisingly applicated in thermal detectors near the room temperature.
关键词： Pulsed laser deposition technique,Electrical properties,La0.72Ca0.28MnO3:Ag0.2 thin ?lms,Surface morphology
更新于2025-09-11 14:15:04