Single photon sources in 4H-SiC metal-oxide-semiconductor field-effect transistors

We present single photon sources (SPSs) embedded in 4H-SiC metal-oxide-semiconductor fieldeffect transistors (MOSFETs). They are formed in the SiC/SiO2 interface regions of wet-oxidation C-face 4H-SiC MOSFETs and were not found in other C-face and Si-face MOSFETs. Their bright room-temperature photoluminescence (PL) was observed in the range from 550 to 750 nm andrevealed variable multi-peak structures as well as variable peak shifts. We characterized a wide variety of their PL spectra as the inevitable variation of local atomic structures at the interface. Their polarization dependence indicates that they are formed at the SiC side of the interface. We also demonstrate that it is possible to switch on/off the SPSs by a bias voltage of the MOSFET

Fabrication and evaluation of Ta2O5:Y2O3 co-sputtered thin films

Co-sputtered tantalum (V) oxide and yttrium (III) oxide (Ta2O5:Y2O3) thin films were fabricated using radio-frequency magnetron sputtering for the first time, and their photoluminescence (PL) and X-ray diffraction properties were evaluated. Broad PL spectra from 380 to 800 nm were observed only from films annealed at 700 °C. The maximum PL intensities were found around a wavelength of 500 nm regardless of the Y concentrations of the films, and the films annealed at 700 °C were primarily amorphous phases. It seems that the broad PL spectra from the Ta2O5:Y2O3 films originated from oxygen vacancies of Ta2O5 and Y2O3 particles that may be produced in Ta2O5 by co-sputtering

Fabrication of Tm-doped Ta2O5 thin films using a co-sputtering method

Thulium-doped tantalum-oxide (Ta2O5:Tm) thin films were prepared using a simple co-sputtering method. A remarkable photoluminescence peak having a wavelength of around 800 nm due to Tm3+ was observed from a film annealed at 900 °C for 20 min. The δ-Ta2O5 (hexagonal) phase of the Ta2O5:Tm sputtered film is very important for obtaining strong photoluminescence

Yellow light emission from Ta2O5:Er, Eu, Ce thin films deposited using a simple co-sputtering method

Erbium, europium, and cerium co-doped tantalum oxide (Ta2O5:Er, Eu, Ce) thin films were prepared using a simple co-sputtering method, and yellow light emission was observed by the naked eye from a sample annealed at 900 °C for 20 min. The hexagonal Ta2O5 phase is very important, but the hexagonal CeTa7O19 phase should be avoided to obtain strong yellow light emission from Ta2O5:Er, Eu, Ce films. The co-sputtered films can be used as high-refractive-index and yellow-light-emitting materials of autocloned photonic crystals that can be applied to novel light-emission devices, and they will also be used as anti-reflection and down-conversion layers toward high-efficiency silicon solar cells

Fabrication and evaluation of green-light emitting Ta2O5:Er, Ce co-sputtered thin films

Erbium and cerium co-doped tantalum-oxide (Ta2O5:Er, Ce) thin films were fabricated using radio-frequency co-sputtering of Ta2O5, Er2O3, and CeO2 for the first time. Enhanced green-light emission due to Er3+ that seems to be sensitized by Ce3+ was observed from the film annealed at 900 °C for 20 min. From XRD measurements of the films, the β-Ta2O5 (orthorhombic), δ-Ta2O5 (hexagonal), and (201) Ta2O5 phases seem to be very important for obtaining green PL from them. Such Ta2O5:Er, Ce co-sputtered films can be used as high-refractive-index materials of autocloned photonic crystals that can be applied to novel green-light-emitting devices, and they will also be used as multi-functional coating films that can work both as anti-reflection and down-conversion films for realizing high-efficiency silicon solar cells

Micro-ion beam-induced luminescence spectroscopy for evaluating SiAlON scintillators

Ion beam-induced luminescence (IBIL) spectroscopy was used for luminescent material characterization and analysis for the investigation of new scintillator families. Under continuous 3 MeV proton microbeam irradiation, the crystal structures of α-SiAlON:Eu, β-SiAlON:Eu, and CaAlSiN3 (CASN) emitted bright luminescence at peak wavelengths of 605, 540, and 670 nm, respectively. As the irradiation progressed, the IBIL intensity of the conventional ZnS:Ag scintillator decreased sharply, whereas that of the SiAlONs and CASN remained within the detection limit. IBIL spectroscopy was performed on individual grains of the SiAlON scintillators. IBIL imaging and spectroscopy of two grains of β-SiAlON:Eu showed that the main peak in the IBIL spectrum of β-SiAlON:Eu obtained from a large-area beam scan consisted of several small peaks, which were observed in spectra from individual grains. Our experimental results suggest that microscopic spectroscopy of IBIL is an effective tool for microscopic material characterization of luminescent targets

Fluorescent Defect Formation in Single Crystalline Diamond by Focused Proton Irradiation

Creation of fluorescent defects at desired position and structures will play an important role for development of quantum devices. Compared to other microfabrication techniques, focused particle beam is excellent tool for defect engineering on wide band-gap semiconductors. There are several studies on micro-processing using various focused particle beam writing (PBW) techniques and some among them successfully demonstrated fabrication of graphite structures in diamond. Recently, we succeeded to control the depth of the micrometer-scaled processed layer by changing energy of the focused ions.These techniques would be applicable to form defects of fluorescent centers in diamond by precise control of PBW microprobe.23rd International Workshop on Inelastic Ion-Surface Collisions (IISC-23

In-air micro-particle-induced X-ray emission imaging and spectroscopy of air-borne particles collected hourly from an automated sampling unit of the atmospheric environmental regional observation system

Particulate matter (PM) collected hourly by an automated sampling unit of the Atmospheric Environmental Regional Observation System (AEROS) was characterized by external micro-particle-induced X-ray emission (PIXE) analysis and imaging. Micro-PIXE analysis revealed the overall elemental composition and differences in the elemental composition ratios of PM2.5 and PM2.5-10 collected as individual spots on Teflon tape filters from the unit, and the blank Teflon tape showed a clean background. Moreover, micro-PIXE imaging visualized regions with different elemental compositions in PM2.5 and PM2.5-10. Accumulation of PM2.5 particles was found frequently on tape filters which accounted approximately for 70% of particular elemental composition including heavy metals like iron, compared to that from whole area. The results suggest that PIXE effectively reveals elemental composition of hourly-collected PM by AEROS system for futuristic application for source apportionment of those over Japan