摘要:

Differential optical switching operation with an optical input of as low as 400 fJ (0.07 fJ/&mgr;m2) was realized by using parallel‐connected AlGaAs/GaAspnpnoptical switches. An improvement in the sensitivity of more than two orders of magnitude has been attained by introduction of a new operating concept. The electrical transient time was 10 ns, almost independent of optical input levels.

ISSN:0003-6951    

DOI:10.1063/1.103537

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We demonstrate modulation for GaAs multiple quantum well (MQW) waveguide modulators on silicon substrates. The modulators, which were fabricated by molecular beam epitaxy, were operated at wavelengths of 890–910 nm, with greater than 20 dB modulation obtained at &lgr;=900 nm for a reverse bias of 2.5 V. Photocurrent measurements were performed on GaAs MQWs grown on Si and compared with results obtained for GaAs MQWs grown on GaAs. The structures were integrated with GaAs/AlGaAs waveguides and are suitable for integration with silicon‐based electronics.

ISSN:0003-6951    

DOI:10.1063/1.103538

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We observe saturation in the electroabsorption of InGaAs/InP multiple quantum wells (MQWs) at high optical intensity. Contrary to the mechanism for zero‐field MQWs, we find that saturation occurs due to the presence of trapped photogenerated holes that screen the MQWs from the applied electric field. By carefully measuring the absorption coefficient of the wells and the emission time for holes, we are able to fit the observed electroabsorption saturation with no adjustable parameters.

ISSN:0003-6951    

DOI:10.1063/1.103539

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We examine the linear electro‐optic response of a polymer thin film to an applied step function poling electric field. Time‐resolved measurement of the electro‐optic response is compared to theory. The electro‐optic response measurement uses a heterodyne interferometric technique not previously reported. Response rise and fall times of the order of milliseconds are resolvable and the temperature dependence of those times reported. Good qualitative agreement between theory and data is presented.

ISSN:0003-6951    

DOI:10.1063/1.103540

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the homodyne detection of phase modulation sidebands induced on a laser beam by a coherently bunched electron beam. This provides a sensitive and nonperturbing measurement of complex Fourier time series components of the electron density. A proof‐of‐principle measurement of the microwave frequency component of electron density in a crossed‐field device, which agrees well with a calculation of the same quantity, is reported.

ISSN:0003-6951    

DOI:10.1063/1.103541

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A chemical vapor deposited diamond film was grown on a silicon substrate by the plasma arcjet method. The deposited film was circular and appeared to be radially zoned under visual examination. A secondary electron microscope was used to examine the surface morphology and microfocus Raman spectroscopy was used to examine the radial compositional variation of the film. Raman spectroscopy shows that the composition of the diamond film changed markedly in the space of hundreds of microns. Changes in the Raman spectra can be correlated with variations in morphology of the diamond film.

ISSN:0003-6951    

DOI:10.1063/1.103542

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The vacuum ultraviolet (VUV) (120–200 nm) and extreme ultraviolet (EUV) (80–120 nm) reflectance characteristics of as‐deposited films of amorphous aluminum nitride (AlN) and diamond‐like carbon (DLC), and of single‐crystal &bgr;‐silicon carbide (SiC) have been measured. AlN and DLC films have been grown by plasma‐enhanced chemical vapor deposition (PECVD) and the SiC film by chemical vapor deposition (CVD). The VUV reflectivities of AlN and SiC exceed 50% while the reflectance of DLC film is low (∼10%). Furthermore, DLC and SiC films display EUV reflectance characteristics that are very desirable. The reflectivity of as‐deposited SiC is 40% and that of DLC is about 20%.

ISSN:0003-6951    

DOI:10.1063/1.103543

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The repetitive cycles of a few monolayers hydrogenated silicon deposition and its oxidation has been employed for the growth of SiO2. The surface reaction is promoted by an alternate irradiation of silicon hydride radical beam produced by the upstream pulsed microwave discharge of SiH4and discharged oxygen beam. The deposition rate is controlled by the flow velocity of silane gas jet and substrate temperature. It is shown that the deposition species ejected with supersonic velocity into a high vacuum reactor conformably fills the SiO2film into a deep Si trench.

ISSN:0003-6951    

DOI:10.1063/1.104284

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report electronic Raman scattering measurements of the plasmon mode in a single GaAs/AlGaAs heterojunction, with a &dgr; layer of acceptors in the GaAs buffer a well‐defined distance from the interface. Under illumination above the band gap of the AlGaAs barrier, a dynamic charge‐transfer effect occurs in which the quasi‐two‐dimensional electron concentration of the hetrojunction decreases. From Raman measurements of the plasmon mode we directly determine the change in carrier concentration with excess illumination. We obtain a time of &tgr;=120 ps for the transfer of electrons from the AlGaAs barrier into the two‐dimensional channel.

ISSN:0003-6951    

DOI:10.1063/1.103544

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report the growth of high quality ZnSe/GaAs superlattices by migration‐enhanced epitaxy (MEE) and their characterization using x‐ray diffraction, electron microscopy, and photoluminescence. A streaky reflection high‐energy electron diffraction (RHEED) pattern and strong, persistent RHEED oscillation during the MEE growth of the superlattices indicate a smooth growing surface. The sharp satellite peaks observed clearly in the double‐crystal x‐ray diffraction rocking curve of a 21‐period ZnSe/GaAssuperlattice confirm the excellent crystalline and interfacial quality of the superlattice. Cross‐section high‐resolution electron microscopy indicates coherent lattice arrangement and abrupt interface at ZnSe‐on‐GaAs as well as GaAs‐on‐ZnSe heterointerfaces. Photoluminescence spectra from a superlattice with a periodicity of 40 nm show a strong peak at a wavelength of 829.5 nm with a linewidth of 6.3 meV at a temperature of 10 K; we believe this to be the first observation of photoluminescence from any multilayer structure involving GaAs‐on‐ZnSe growth.

ISSN:0003-6951    

DOI:10.1063/1.103545

出版商:AIP    

年代:1990

数据来源: AIP