Papers by Author: Chen Yang Xue

Abstract: A facile doping method utilizing inexpensive raw materials was proposed to achieve variation in optical bandgap and UV-visible light absorption property of MoS₂ nanosheets. Carbon-assistant heating with degreasing cotton has demonstrated the development of carbon-doped MoS₂ nanosheets with enhanced rich defects. The results obtained shown that modified MoS₂ nanosheets with the lateral width of ~600 nm are exhibited shift of the intensively blue peaks of photo-luminescence (PL) comparing to those MoS₂ nanosheets with a lateral dimension of larger than 1 μm. Optical bandgap of the carbon-doped MoS₂ nanosheets was found to be broader than that of the pure MoS₂ nanosheets and the prepared samples also exhibited a broadband UV-visible light absorption property.

Abstract: Atomic Layer Deposition (ALD) is an enabling technology which provides coating and material features with significant advantages compared to other existing techniques for depositing precise ultra-thin two-dimensional (2D) nanostructures. ALD provides digital thickness control to the atomic level by depositing film one atomic layer at a time, as well as pinhole-free films even across large and complex areas. The technique’s capabilities are presented on the example of ALD-developed ultra-thin 2D tungsten oxide (WO3) over the large area of standard 4” Si substrates. The discussed advantages of ALD enable and endorse the employment of this technique for the development of hetero-nanostructure 2D semiconductors with unique properties.

Abstract: In this paper, a new capacitive micromachined ultrasonic transducer (CMUT) is designed by using SU-8 material, and the theory of elastic thin plate is used to deduce the relationship between the pressure and capacitance of the structure. Simulation has been done about SU-8 CMUT by finite element method software ANSYS. The deformation of CMUT under acoustic pressure, the relationship between frequency, thickness and sensitivity, as well as the acoustic impedance and reflection coefficient of SU-8 material also have been studied through the simulation. The results turn out that SU-8 has the advantages of big dynamic range, high sensitivity and small acoustic impedance, so it has broad application in the ultrasonic field.

Abstract: In this paper, the crosstalk in potential measurements caused by the topographic feedback and the resonance frequency in Kelvin probe force microscopy (KPFM) was investigated in frequency modulation (FM), amplitude modulation (AM) and heterodyne amplitude modulation (heterodyne AM) modes. We showed theoretically that the distance-dependence of the modulated electrostatic force in AM-KPFM is significantly weaker than in FM-and heterodyne AM-KPFMs. We experimentally confirmed that the crosstalk in FM-KPFM and heterodyne AM-KPFM is weak than that in AM-KPFM due to the bigger difference of the modulated frequencies in topographic and potential measurements in FM and heterodyne AM-KPFMs. We also compared the corrugations in the local contact potential difference (LCPD) on the surface of Si (001) show that difference on topographic (potential) images is approximately 15 pm (10 mV) between the faulted and unfaulted parts using heterodyne AM-KPFM, on the other hand, this difference cannot be observed using AM-KPFM mode. Original of this was attributed to the low crosstalk between the topographic and the LCPD measurements in heterodyne AM-KPFM.

Abstract: The atomic spin interaction is very important for understanding the superficially magnetic feature of nanostructure at atomic level. Magnetic exchange force microscopy (MExFM) is an innovative means of measuring surface spin force. But it is difficult to separate the surface topography and spin information. We develop the magnetic exchange force microscopy using ferromagnetic resonance (FMR-MExFM). The theoretical and experimental results demonstrate that this method can separate the two kinds of information effectively. Here, in order to obtain the high sensitivity in detecting the ferromagnetic resonance, we fabricate the microwave irradiation device to optimize the position between the device and the cantilever. We have succeeded in observing the ferromagnetic resonance effect and determining its resonant frequency using the homemade microwave irradiation device and the network analyzer. This research is very important for developing FMR-MExFM and novel magnetic sensor, detecting the magnetic information, etc.

Abstract: Lithium tantalate (LT) is a kind of excellent pyroelectric materials that can be made into high performance pyroelectric detector. As the detector voltage response and detection rate inversely proportional to the thickness of the infrared sensing element, So the thinning of lithium tantalate crystals becomes a key of success. This design uses CMP method to produce 50 μm thickness of LT wafer, and via charge integration method with computer automatic test system to test the pyroelectric coefficient of crystals with different thickness and surface roughness. The pyroelectric coefficient of crystal achieved 203 μC·m^-2k^-1 proves the favorable pyroelectric properties.

Abstract: In the paper, it demonstrates highly integrated tenth-order filters in silicon-on-insulator (SOI). The micro-ring resonators have a small radius of 5μm and a very large free spectral range ~ 18nm at 1.55μm communication band. For through port responses, the grating and the high-order optic filters with ten coupled micro-ring resonators are designed and demonstrated, and grating responding well matches with the experiment resonators. Devices are patterned with electron-beam lithography (EBL). And 2μm SiO2 layer is covered on the silicon waveguide, thus reducing the propagation loss in micro-ring resonators.

Abstract: With the extensive research and application of SOI nano-optical ring resonators, the problem of high integration becomes the bottleneck restricting its development. To research the effect of deposited SiO2 insulating layer on the resonance characteristic of SOI nano-waveguid ring cavity while integrating, a rib waveguide ring resonator with 500nm SiO2 insulating layer deposited was designed and fabricated in this paper. By testing the resonance transmission spectrum power of this structure, it is found that SiO2 insulating layer deposited has no effect on the grating vertical coupling efficiency while improves the quality factor to 14.000±1.000.

Abstract: We designed High-Q micro-ring resonators based on SOI material. A new method of using a top SiO2 layer to cover the waveguide is applied and the tested Q factor is as high as 1.0135×104. Micro-ring resonator has been fabricated using Electron-Beam Lithography and Inductive Coupled Plasma. OptiFDTD was used to simulate the micro-ring resonator and we compared the transmission spectrum of this resonator with the resonator without SiO2 covering.

Abstract: A novel MEMS vector hydrophone with bionics structure was introduced in 2007. As the acoustic-electric transducer infrastructure has been optimized, the performance of the hydrophone has been greatly improved compared with the previous. This hydrophone calibration was finished in National Defense Underwater Acoustics Calibration Laboratory of China. According to test results, the sensitivity of the hydrophone is -165dB（including pre-amplification 20 dB）,The frequency response ranges from 20Hz to 2kHz (±5dB). And this hydrophone has a good directional pattern in form of "8"-shape.