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The structure and device characteristics of InGaAs/GaAs strained quantum wire (QWR) lasers grown by organometallic chemical vapor deposition on 0.25‐μm pitch periodic corrugations are reported. The crescent‐shaped InGaAs wires, 14–17 nm thick and 70–80 nm in full width, are formed in situ due to surface diffusion of In and Ga species to the bottom of the grating grooves. Room‐temperature pulsed operation has been achieved with threshold current densities of 1.9 kA/cm2 for 1.1 mm long lasers with uncoated facets. For laser stripes aligned perpendicular to the wires, the lasing wavelength remains almost constant at 920 nm for temperatures 80

We demonstrate low‐loss optical mode‐size tapers in InGaAsP/InP optical waveguides fabricated by selective organometallic chemical vapor deposition. The tapers increase the vertical mode size by ≊300%. Taper losses as low as 0.4 dB (on‐chip, excluding coupling) were achieved, with 2.6 dB coupling loss to a flat‐end, single‐mode fiber at 1540 nm wavelength.

Two‐dimensional (2D) lateral band‐gap patterning and carrier confinement were observed in InGaAs/GaAs patterned quantum‐well (QWL) dots grown by molecular beam epitaxy on prepatterned, nonplanar GaAs substrates. Growth of the strained QWL layers on craters of 0.2–5 μm diameters etched onto the substrate results in 2D lateral potential wells formed at the inside and outside regions of the craters due to preferential migration of Ga and In adatoms. Evidence for lateral carrier confinement and efficient radiative recombination in the resulting dot‐ and ring‐shaped potential wells was provided by low‐temperature cathodoluminescence spectroscopy and imaging. The results of this study indicate the feasibility of producing damage‐free quantum dot and quantum ring heterostructures by growth of QWLs on patterned, nonplanar substrates.

Monolithic optoelectronics requires optical linkage between waveguides and photodiodes. Vertical coupling offers the advantages of single-step epi-growth and ease of junction placement.1,2 Its drawback is weak coupling, resulting in long detector lengths L and high capacitance. thinner guides can reduce L,1,2 but increase input coupling difficulty. We recently demonstrated than an optical "matching layer' introduced between a thick n-/n^+ InP waveguide and an InGaAs absorber significantly enhances vertical coupling.3 Here we show that this approach provides efficient coupling between InGaAs detectors and InGaAsP waveguides of the type currently employed in photonic integration.

We report the band‐edge photoluminescence spectra of CdSnP2 crystals lightly doped with Cu or Ag. The emission from CdSnP2:Cu is dominated by a broad band 0.13 eV below the band gap at 1.240 eV (2°K). The emission from CdSnP2:Ag is much stronger and is dominated by a narrow band‐to‐band emission with three impurity peaks at slightly longer wavelengths. At the very high excitation levels, possible with a pulsed N2 laser, a new band appears ∼ 15 meV below the band gap in CdSnP2:Ag, grows superlinearly in the excitation level, and has other features indicating stimulated emission. Indeed, in crystals suitably prepared to form Fabry‐Perot cavities, narrow‐line laser emission is observed. Studies in a magnetic field reveal that the spontaneous band‐to‐band transition and the new stimulated line shift to higher energies at precisely the same rate indicating that they result from the same recombination mechanism. From the observed shift to higher energies, it is argued that exciton‐exciton scattering can be unambiguously eliminated as the laser mechanism. As briefly reported previously, it is shown that the magnitude and field dependence of the shift requires proper account of electron‐plasmon (plasmaron) coupling.

We report the preparation and electrochromic properties of iridium oxide films deposited by reactively sputtering iridium in a humidified oxygen discharge. These sputtered iridium oxide films (SIROFs) have the fast coloring and bleaching kinetics and excellent stability previously observed for anodically grown iridium oxide films (AIROFs). SIROFs deposited on SnO2‐coated glass can be modulated from clear to blue‐gray with properties similar to those of AIROFs. In addition, SIROFs deposited on metal substrates exhibit a variety of colors which can be electrically altered. This adds a new dimension to the range of potential applications for iridium oxide displays.

A new solid‐state electrochromic cell has been fabricated using an anodic iridium oxide film (AIROF) display electrode. The cell has the symmetric sandwich structure AIROF‖Nafion‖AIROF, with the Nafion solid electrolyte opacified by an in situ precipitation technique. A symmetric square‐wave voltage of 1.5 V amplitude produces clearly perceivable color changes from pale to dark blue‐gray in ≈1 sec when viewed in diffuse reflection. Good open‐circuit optical memory is exhibited: (typical loss in attenuation of 8%/day).

We describe a method of metal deposition by electron beam exposure and pyrolysis of a gold containing organometallic polymer. Commercial gold containing solutions were used as negative electron beam resists with line dose sensitivities of about 0.2 μC/cm as developed in methylene chloride. We have demonstrated the formation of metal patterns on Si, GaAs, and polyimide with linewidths as small as 0.25 μm.

Anodic iridium oxide films (AIROF’s) can be grown and operated on transparent substrates. Using SnO2‐coated glass as the substrate we can monitor large, rapid, and persistent variations of the light intensity transmitted through the AIROF. The voltammogram of the AIROF on SnO2‐coated glass is essentially identical to that of an AIROF on iridium. This proves that the electrochemistry producing the coloration does not involve the substrate.

The optical recording characteristics of TeNx films are described. Te‐nitride formation has been achieved by reactive sputtering. The optical writing properties vary drastically with increasing nitrogen incorporation. Films with moderate nitrogen content maintain good hole and rim forming properties while enhancing the sensitivity of the medium. These layers show a considerable resistance against rapid environmental stress.

Low‐temperature cathodoluminescence spectroscopy was used to investigate the luminescence efficiency of reactive ion etched quantum dots, varying in diameter from 200 μm down to 60 nm. The luminescence efficiency was found to be degraded both with decreasing nanostructure size and with increasing etch depth. A solution to the standard model for diffusion and recombination was applied to the data to determine the surface recombination velocity S. We found that for dots smaller than the diffusion length, the standard diffusion model becomes insensitive to the value of S and fails to predict that there is a size of dot in which the luminescence is completely extinguished. To understand qualitatively the luminescence degradation in etched nanostructures we describe a damage layer thickness ξ. The value of ξ determines the smallest quantum structure that will still emit light. We show that ξ increases with increasing etch depth and is therefore dependent on etching conditions.

A new wet chemical etchant for high‐temperature superconducting films is reported, which leaves transition temperature unaffected within experimental accuracy (1 K) and does not require reoxygenation. The solution consists of ethylenediaminetetraacetic acid (EDTA) in water, and is suitable for micropatterning using standard photolithography. We have fabricated 3–50 μm patterns on laser‐deposited Y‐Ba‐Cu‐O films. The bulk of the films etches at 0.14 μm/min in a saturated solution at room temperature. Porous surface layers are removed three times faster than the dense portions of the films. Etch rate depends linearly on the solution concentration and exponentially on the solution temperature. These rates are reduced if etching is interrupted and the samples are exposed to atmosphere.

Single‐mode rib waveguides with low propagation loss (0.2 dB/cm) were fabricated on GaAs/AlGaAs single heterostructures by dry etching. The attenuation of these guides was measured to study the effect of rib structure on propagation loss at 1.52 μm. An increase in loss with increased rib height and decreased rib width was associated with scattering due to a rib surface roughness of approximately 50 nm for ion milled waveguides. Fabrication with reactive ion etching reduced the rib roughness and its associated scattering loss by a factor of 3 or more in waveguides with strong optical confinement (effective index difference of 0.012) of the fundamental guided mode.

We report measurements of the temperature dependence of coloration and bleaching times of electrochromic iridium oxide films in the range +20 to −43 °C. The intrinsic response times increase gradually with decreasing temperature according to an activation energy of ∼0.25 eV. For a contrast ratio of ∼4:1, suitable for a practical device, we find that the response times remain below ∼0.25 sec for T⩾−10 °C and below 1 sec for T⩾−25 °C. We have also found that the temperature variation of the response times is independent of pH, so that an optimized electrolyte can be chosen for a practical device. Moreover, its independence of pH suggests that the electrochromism of iridium oxide is due to insertion and fast‐ion diffusion of the same ion species in either basic or acidic aqueous electrolytes.

We describe the electrical and optical performance of a prototype seven‐segment iridium oxide electrochromic display. The response time is ∼0.4 s for a 2.5‐cm digit and varies as the square of the digit dimensions. It is shown that driver electronics can be implemented very simply for electrochromics.

p‐InP/n‐CdS heterodiodes electroluminesce under forward bias. In diodes prepared by in vacuo growth of CdS layers on InP substrates, the spectrum is determined by recombination through deep interface states. Anneals at 500–600 °C shift the emission to energies close to the band gap of InP.

A low−resistance (0.1 Ω/mm2) Ohmic contact to moderately resistive (1−10 Ω cm) p−type InP has been developed using Au/Zn/Au metalization.

Epitaxial thin films of ZnSe grown on GaAs substrates were reactive ion etched using BCl3 /Ar gas mixtures. Using an optimized etching process, photolithographically defined micrometer sized structures were etched several micrometers deep with straight sidewalls and smooth surfaces. Cathodoluminescence was measured from both etched and unetched surfaces at room temperature. Luminescence intensities of etched surfaces are shown not to be degraded by the reactive ion etching process. Cathodoluminescence intensities of etched pixels with exposed sidewalls were found to be greater than the intensities measured from unetched flat surfaces. This suggests the possibility of efficient etched light‐emitting structures.