摘要:

ZnS:Cu nanocrystals were synthesized in polymeric networks. X-ray photoemission spectroscopy and atomic absorption data show that the Zn and Cu ion mass contents were about 8.2&percent; and 0.12&percent;, respectively. The particle size of ZnS:Cu nanocrystals was about 3.0 nm, measured by UV-vis spectrum. Due to the quantum size effects, the band gap energy of ZnS nanocrystals was about 4.2 eV. Compared with the photoluminescence of ZnS which peaks at 390 nm, the photoemission of ZnS:Cu/polymer thin films was peaking at 415 nm because of Cu acting as luminescent centers. The ZnS:Cu/polymer was also used to fabricate light-emitting diode (LED), as the emitting layer of LED, the blue light of electroluminescence was observed at room temperature, and its turn-on voltage was less than 4 V. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118866

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Twenty bilayers of titanium oxide and aluminum oxide with the layer-pair thickness of 4.43 nm on a silicon substrate were fabricated for novel multilayer reflectors at water-window wavelengths by an atomic layer deposition method of controlled growth with sequential surface chemical reactions. The high reflectance of over 30&percent; at a wavelength of 2.734 nm and an incident angle of 71.8° from the normal incidence was demonstrated experimentally. The full width at half-maximum of the reflectances at 2.734 nm was 0.0381 nm, which corresponds to &Dgr;&lgr;/&lgr;=1.4&percent;. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118898

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on an efficient supersonic chemical oxygen-iodine laser, energized by a jet-type singlet oxygen generator, operating without primary buffer gas and applying simple nozzle geometry and transonic mixing of iodine and oxygen. Output power of 177 W with chemical efficiency of 17&percent; was obtained in a 5 cm gain length forCl2flow rate of 11 mmol/s. The power is almost unaffected by water vapor in the medium. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118868

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A method to estimate the spontaneous emission factor&bgr;is proposed and applied to the 780 nm oxidized vertical-cavity surface-emitting lasers. The proportionality of the measured cavity loss multiplied by optical power to injected current is used. Our results agree better with theoretical calculations than those of conventional light-current curve fitting. The spontaneous emission factor of 0.0021 is obtained for a 2-&mgr;m-square device at room temperature. Since only the below-threshold information of cavity loss and output power are used in our method, the obtained&bgr;values are independent of any complex and unexpected above-threshold effects such as thermally induced mode-size contraction, as they should be. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118869

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Resonant-cavity photodetector arrays are demonstrated in the InGaAs/InAlAs/InP material system grown by solid-source molecular beam epitaxy. To reduce crosstalk between channels, these devices are designed with a high-Qcavity to obtain narrow-band photoresponse. In addition, a novel double-absorber design has been proposed and implemented to avoid position sensitivity related to the cavity standing wave and eliminate the need forin situcavity-mode adjustment. Both Schottky andP-i-Ndiode structures are studied and compared. Eight element arrays with linearly distributed resonant wavelengths spanning over 30 nm are fabricated by using a three-level anodic oxidation process. An experimental channel rejection ratio of 14.5 dB at 4 nm away from the resonant peak has been achieved. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118870

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Optical properties of a ZnSe/MgS superlattice (SL) were studied by reflection and photoluminescence (PL) spectroscopies. Excitonic structures were clearly observed in the reflection spectra up to room temperature, and the exciton absorption peak energy and linewidth were well coincident with the PL peak energy and linewidth. The origin of the lowest luminescence peak was indicated to be C1-HH1 exciton up to room temperature. The lineshape broadening due to longitudinal-optical-phonon scattering of excitons is much decreased in this SL compared to bulk ZnSe. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118867

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report photoluminescence fromSi1−x−yGexCyfilms grown epitaxially on Si (100) by chemical vapor deposition. We observe significant energy shifts but no dramatic changes in the photoluminescence line shape caused by the presence of carbon. Using standard deformation potential theory to correct the epitaxial strain shifts, we conclude that the band gap of relaxedSi1−x−yGexCyalloys has a lower energy than the band gap of relaxedSi1−xGexwith the same Si/Ge ratio. We propose an explanation of these results based on the assumption that carbon forms a resonant level within the conduction band ofSi1−xGex.©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118871

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Data are presented on an oxide-confined vertical-cavity surface-emitting laser that uses a quantum dot active region. The laser is grown by molecular beam epitaxy, with the quantum dot active region formed from a five monolayer deposition ofIn0.50Ga0.35Al0.15As.Lasing occurs at wavelengths corresponding to quantum dot transitions, with a room temperature pulsed threshold as low as 560 &mgr;A for a 7 &mgr;m diameter oxide aperture. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118872

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

4.5 mW of power in a single spatial mode has been obtained from a vertical cavity surface emitting laser (VCSEL) in an external cavity setup, using a graded index (GRIN) lens with a spatial filtering high reflecting aperture deposited on its endface. The spatial filter on the GRIN lens endface forces a larger single transverse mode in the VCSEL than is obtained without it. A brightness of5.1×105 W/cm2str is demonstrated, which is 91&percent; of the maximum achievable. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118873

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The formation of a stationary cavity by a sequence ofCO2laser pulses was investigated in liquids of different viscosity and surface tension. Decreasing the surface tension of the liquid and increasing its viscosity increases the depth of the cavity and decreases the threshold energy needed for its formation. A theoretical model based on the Bernoulli–Stokes equation was developed. Good agreement between experimental and theoretical results was obtained. A method of reducing thermal damage, involving liquid layer effects during laser cutting of different materials, is proposed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118874

出版商:AIP    

年代:1997

数据来源: AIP