A5058805983- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Nanowire Synthesis and Applications
- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Advanced Semiconductor Detectors and Materials
- Silicon and Solar Cell Technologies
- Semiconductor Quantum Structures and Devices
- Atmospheric Ozone and Climate
- Semiconductor materials and interfaces
- Air Quality Monitoring and Forecasting
- Thin-Film Transistor Technologies
- Phase-change materials and chalcogenides
- Chalcogenide Semiconductor Thin Films
- Ion-surface interactions and analysis
- Analytical chemistry methods development
- Heavy metals in environment
- Climate Change and Health Impacts
- Atmospheric aerosols and clouds
- Electron Spin Resonance Studies
- Advanced Chemical Sensor Technologies
- Quantum Information and Cryptography
- Advanced NMR Techniques and Applications
- Photopolymerization techniques and applications
- COVID-19 impact on air quality
Peking University
1994-2024
State Key Joint Laboratory of Environment Simulation and Pollution Control
2020-2023
Forschungszentrum Jülich
2021
Entry Exit Inspection and Quarantine Bureau
2012
KU Leuven
1998-2000
Nanjing University
1997-1998
Strong photoluminescence from silicon-ion-implanted thermal ${\mathrm{SiO}}_{2}$ film was investigated under various conditions. The spectrum of as-implanted samples or annealed in ${\mathrm{N}}_{2}$ at a temperature below 1000 \ifmmode^\circ\else\textdegree\fi{}C consists three bands centered about 470, 550, and 630 nm. Annealing above for long enough time brings one band peaking 730 peak wavelengths these four are all independent annealing excitation As the is increased, 470-, 550-, 630-nm...
A multiphase chemical kinetic box model (PKU-MARK) was constructed to numerically drive the hydroperoxyl radical (HO2) uptake coefficients (γHO2) using observation data from a comprehensive summer field campaign in rural China. The associated chemistry mechanism of HO2 investigated. and physical features aerosol particles were explicitly considered simulations. importance transition metals heterogeneous processes confirmed by flux investigation. Heterogeneous proposed have impacts on ozone...
Abstract. Sulfate is one of the main components haze fine particles, and its formation mechanism remains controversial. A lack detailed comprehensive field data hinders accurate evaluation relative roles prevailing sulfate pathways. Here, we analyzed production rates using a state-of-the-art multiphase model constrained to observed concentrations transition metal, nitrogen dioxide, ozone, hydrogen peroxide other important parameters in winter summer North China Plain. Our results showed that...
Atmospheric Oxidation Capacity (AOC) quantifies the ability of atmosphere to oxidize primary species. It plays a crucial role in initiating atmospheric chemical processes and impacts formation secondary pollutants, such as ozone (O₃) aerosols. AOC is fundamentally determined by concentrations reactivity oxidants, including O₃, hydroxyl radicals (OH), nitrate (NO₃). Due inherent challenges direct measurement, typically inferred through numerical modeling....
Intense ultraviolet photoluminescence centered at 370 nm was observed from magnetron-sputtered silicon oxide films after they were annealed about 1000 °C in N2 atmosphere. This is found to be associated with the formation of nanocrystal particles specially structured SiO2, which highly resembles layer porous silicon. The luminescence centers interface between and SiO2 matrix are responsible for strong luminescence.
A systematic study of the dependence photoluminescence from porous silicon (PS) on oxidation extent and measurement temperature is given. Oxidation PS samples at room up to 200 \ifmmode^\circ\else\textdegree\fi{}C results in spectra with maxima centered around 1.7 eV. The shift 10--300 K always toward 1.7-eV position. These conflict predictions quantum confinement model for luminescence, but can be explained by assuming that several types luminescence center outside nanoscale Si units are...
Abstract. Heterogeneous uptake of hydroperoxyl radicals (HO2) onto aerosols has been proposed to be a significant sink HOx, hence impacting the atmospheric oxidation capacity. Accurate calculation HO2 coefficient γHO2 is key quantifying potential impact this process. Laboratory studies show that can vary by orders magnitude due changes in aerosol properties, especially soluble copper (Cu) concentration and liquid water content (ALWC). In study we present state-of-the-art model called MARK...
Post-transit photocurrent analysis, based on the time-of-flight transient photoconductivity technique, was successfully carried out for a series of amorphous selenium $(a\ensuremath{-}\mathrm{Se})$ thin films. The method allows determination density gap states beyond shallow tail from emission-dominated post-transit currents. Prominent hole and electron traps were resolved some 0.4--0.5 eV above valence-band edge 0.55--0.65 below conduction-band edge. These two represent thermally accessible...
This study developed a method for simultaneous determination of 19 chemical elements (Al, V, Cr, Mn, Co, Cu, Ga, As, Rb, Y, Zr, Cd, Te, Ce, Pr, Nd, Sm, Er and Pb) in simulated foods [4%, 6% 8% (w/v) aqueous acetic acid] by microwave‐assisted digestion inductively coupled plasma mass spectrometry. We examined the migration these from ceramic packaging into two types mature vinegar. The showed matrix effects, compared with stock solution solvents (5% ultra‐pure nitric acid). was affected time,...
We have systematically measured the room-temperature photoluminescence spectra with a two-band structure from porous silicon (PS), as function of excitation wavelengths in wavelength range 260 to 460 nm. Each spectrum can be fitted by two Gaussian functions centered at about 610 and 700 nm, intensities bands change intensity maxima occur when is 340 400 respectively. When exceeds 420 band nm very weak. The above phenomena accounted for quantum confinement/luminescence centers model [G. G....
Hydrogen peroxide (H2O2), hydroxyl radicals (OH), hydroperoxyl (HO2), and superoxide (O2-) interacting with aerosol particles significantly affect the atmospheric pollutant budgets. A multiphase chemical kinetic box model (PKU-MARK), including processes of transition metal ions (TMI) their organic complexes (TMI-OrC), was built to numerically drive H2O2 behaviors in particle liquid phase using observational data obtained from a field campaign rural China. Instead relying on fixed uptake...
Up to now, in most of the research work done on effect hydrogen a Schottky barrier, was introduced into semiconductor before metal deposition. This letter reports that can be effectively barriers (SBs) Au/n-GaAs and Ti/n-GaAs by plasma treatment (PHT) after deposition 〈100〉 oriented n-GaAs substrates. The barrier height (SBH) SB containing shows zero/reverse bias annealing (ZBA/RBA) effect. ZBA makes SBH decrease RBA it increase. variations SBHs are reversible. In order obtain obvious...
After exposure to hydrogen plasma and chemical etching remove layers of different thicknesses, n-type GaAs wafers with 〈100〉 〈110〉 orientation were deposited Au form Au/(n-GaAs) Schottky barriers (SB's). zero-bias annealing (ZBA), the Schottky-barrier height (SBH) SB's containing falls; after reverse-bias (RBA), SBH rises; is reversible within experimental precision in at least three ZBA-RBA processes. Furthermore, control effect on barrier depends quantitatively wafer thickness layer...