摘要:

A new wavelength tunable laser diode with a basically continuous tuning behavior is presented. This essential progress is achieved by transversely tuning the effective index of a distributed feedback laser using a twin waveguide. Due to the built‐in synchronization of the Bragg wavelength and the optical cavity length, the wavelength is controlled by only a single current. The device technology and preliminary experimental results demonstrating the transverse tuning mechanism are presented.

ISSN:0003-6951    

DOI:10.1063/1.101065

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A single quantum well laser with a 2‐mm‐wide aperture has exhibited low threshold current density and nearly 100% packing fraction. The lateral structure relies on epitaxial growth on a corrugated substrate to frustrate radiative lateral processes and it thus eliminates the need for isolation at least for incoherent operation. Threshold current densities are comparable to those for low‐power devices, and slope efficiencies remain undiminished to our current limit where 10.7 W per facet is attained. The aperture size is limited only by our fixturing arrangement.

ISSN:0003-6951    

DOI:10.1063/1.101066

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Crystalline phase Fe16N2has been found in nitrogen‐implanted epitaxial iron films on mirror‐polished (100) MgO substrates. Implantations of N+2at an acceleration voltage of 140 keV transformed the bcc iron into a partially ordered nitrogen martensite with a body‐centered‐tetragonal (bct) structure. The amount of the ordered part was increased to some extent by an annealing treatment in vacuum at 150 °C for 2 hr. An implantation with a dose of 4×1016N2/cm2transformed 60% iron in a film into the bct martensite. The constituent of the ordered phase (Fe16N2) in the bct martensite was 16 wt. %. After the annealing, the constituent increased to 24%. It is proposed that a formation of lower temperature and metastable compound such as Fe16N2can be made available through energetic ion implantation.

ISSN:0003-6951    

DOI:10.1063/1.101543

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Thermal degradation is examined in a development stage in which local damage in the crystal lattice already exists, although the known surface deformations are not yet visible. The existence of these crystal defects is shown by means of luminescence microscopy. Depth profiles reveal that the damage is not restricted to the surface. On ‘‘dark disks,’’ e.g., a spherical spreading of the degradation by some 10 &mgr;m into the crystal volume is observed. Correlation with the position of dislocation etch pits shows that all dislocations are ‘‘decorated’’ with thermally induced defects. ‘‘Dark disks,’’ however, represent no advanced stage of degradation after having been ‘‘decorated,’’ but develop separately from a different defect type, visible as ‘‘S’’ or ‘‘flat’’ etch pits. This type of defect has not yet been taken into consideration with regard to crystal quality criteria. We suspect that thermal degradation developing from this defect type is the missing link between substrate quality and certain problems in processing and device failure.

ISSN:0003-6951    

DOI:10.1063/1.101043

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report on the results of a recent study on the deposition of [100] textured MgO films on fused quartz substrates by using the metalorganic chemical vapor deposition technique. Magnesium &bgr;‐diketonate was used as the metal source and the growth rate of the film was about 0.4 &mgr;m/h at 740 °C in a horizontal warm wall reactor. X‐ray diffraction experiments provided evidence that the MgO films on fused quartz were fully textured with [100] orientation perpendicular to the substrate surface. The films had a very smooth surface morphology and optical transparency with an index of refraction of 1.71.

ISSN:0003-6951    

DOI:10.1063/1.101044

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The effectiveness of carbon as a barrier for the outdiffusion of Cu is studied using C/Cu/substrate and Au/C/Cu/substrate structures. For the C/Cu structure deposited on SiO2‐coated Si with a 700 A˚ C layer, heating to 700 °C for 72 h and 750 °C for 6 h shows no outdiffusion of Cu to the carbon surface in N2‐H2.Only reaction between Cu and the SiO2layer underneath is observed. Application of the carbon barrier between Cu and Au in the Au/C/Cu/substrate structure shows that the dilution of the Au layer due to the Cu outdiffusion is similar to but less than that of the Au/Ni/Cu/substrate structure using Ni as a barrier. The stability of the Au/C/Cu/substrate structure is enhanced relative to that of the Au/Ni/Cu/substrate one by more than 150 °C. Both the advantage and concerns using carbon as barriers for the interconnect and contact metallurgies are discussed.

ISSN:0003-6951    

DOI:10.1063/1.101045

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Photoelectron transport in (Cs)Na2KSb real space is investigated using the Monte Carlo simulation technique for various photon energies. The quantum yield and modulation transfer function (MTF) of the (Cs)Na2KSb photocathodes, and the energy distribution and transit time spread (TTS) of the emitted electrons have been obtained. In particular, the quantum yield of the photocathode has a good agreement with the measured results. Computed results indicate that the energy distribution spread and TTS of the emitted electrons from a typical (Cs)Na2KSb photocathode are 0.3–0.6 eV and 300–180 fsec, respectively.

ISSN:0003-6951    

DOI:10.1063/1.101046

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The Hg1−xCdxTe films with a small concentration of Cd and a narrow band gap have been prepared on GaAs(100) substrates by using the ionized cluster beam (ICB) technique. For the case of ionizing clusters of either CdTe or HgTe as source materials, the band gap can be controlled between 0.2 and 0.3 eV by adjusting the acceleration voltage for cluster ions. The kinetic energy and the ionic charge of the cluster ions are found to have much influence on the composition and the optical properties of the films.

ISSN:0003-6951    

DOI:10.1063/1.101047

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

High quality ZnSe layers have been grown by molecular beam epitaxy on dry‐etched ZnSe substrates. Surface damage caused by cutting and polishing of the ZnSe substrate was removed by dry etching using BCl3gas to 10 &mgr;m depth. The dry‐etched ZnSe substrates exhibited smooth surface morphology and showed excitonic emissions stronger than that from as‐polished substrates in photoluminescence (PL) measurements at 11 K. The low‐temperature PL spectra obtained from homoepitaxial ZnSe layers grown on the substrates dry etched at the optimum condition showed a strong free‐exciton emission at 2.804 eV and a dominant donor‐bound exciton emission at 2.798 eV. Since each excitonic emission shows a single peak, the homoepitaxial layers appear to be free from strain.

ISSN:0003-6951    

DOI:10.1063/1.101048

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Ballistic one‐dimensional channels are fabricated using a highly resistive region induced by focused Ga ion beam scanning. Both wide and narrow channels are fabricated using this process. Transport characteristics of these channels are controlled by a voltage applied to the Schottky electrode on the channel. The channels show multiple‐step structures in their transport characteristics at low temperature when the gate voltage is varied. This is probably due to the ballistic transport through one‐dimensional quantized electron states. For narrower channels, the number of the observed steps becomes fewer. Instead, the structures are observable at higher temperature.

ISSN:0003-6951    

DOI:10.1063/1.101049

出版商:AIP    

年代:1989

数据来源: AIP