Bo Baoxue

Rhombus-like stripe BA InGaAs-AlGaAs-GaAs lasers

A 1.5-W continuous-wave power output in a beam pattern of 3/spl deg/ is obtained from a new designed rhombus-like stripe strained quantum-well diode laser (/spl lambda/=980 nm) with a 150-/spl mu/m-wide emission aperture grown by molecular beam epitaxy. The /spl eta//sub d/ is as high as 78%, and the maximum output power by the new stripe laser is 5.0 W for antireflection/high-reflection coated devices.

Structural, Optical and Electrical Properties of Hydrogen-Doped Amorphous GaAs Thin Films

Amorphous GaAs films are deposited on substrates of quartz glass and silicon by rf magnetron sputtering technique in different gas ambient. First, the amorphous structure of the prepared samples is identified by x-ray diffraction. Second, analysis by radial distribution function and pair correlation function method is established to characterize the microstructure of the samples. Then, the content and bond type of hydrogen are analysed using Fourier transform infrared absorption spectroscopy. It is found that the bonded hydrogen content increases with increasing partial pressure PH of H2. However, the hydrogen content saturates at PH > 1 × 10−1 Pa. Hydrogen addition shifts the optical absorption edge to higher energy, decreases the dark conductivity and improves the photo-sensitivity The optical gap, dark conductivity and photo-sensitivity of the films are dependent on the bonded hydrogen content. These results demonstrate that hydrogen has obvious passivation effects on rf sputtered amorphous GaAs thin films.

Influence of sputtering pressure on optical constants of a-GaAs1−xNx thin films

Amorphous GaAs1−xNx (a-GaAs1−xNx) thin films have been deposited at room temperature by a reactive magnetron sputtering technique on glass substrates with different sputtering pressures. The thickness, nitrogen content, carrier concentration and transmittance of the as-deposited films were determined experimentally. The influence of sputtering pressure on the optical band gap, refractive index and dispersion parameters (Eo, Ed) has been investigated. An analysis of the absorption coefficient revealed a direct optical transition characterizing the as-deposited films. The refractive index dispersions of the as-deposited a-GaAs1−xNx films fitted well to the Cauchy dispersion relation and the Wemple model.

Novel passivation process for GaAs(110) surface with sulf-solutions

In order to enhance the effect of sulfur passivation, the influence of solution polarity on the passivation was investigated; With the following conclusion: the smaller polarity of the solution, the better effect of the passivation. A novel passivation solution made up of (NH<inf>4</inf>)<inf>2</inf>S+Se+t-C<inf>4</inf>H<inf>9</inf>OH has been prepared. The PL spectrum intensity of the samples treated by (NH<inf>4</inf>)<inf>2</inf>S+Se+t-C<inf>4</inf>H<inf>9</inf>OH is 23 times stronger than that of non-passivated samples and more efficient than (NH<inf>4</inf>)<inf>2</inf>S passivation alone. This result indicates that (NH<inf>4</inf>)<inf>2</inf>S+Se+t-C<inf>4</inf>H<inf>9</inf>OH solution has a better passivation effect on GaAs(110) surface.

High performance highly strained InGaAs quantum-well ridge waveguide lasers

Highly strained InGaAs ridge waveguide lasers were fabricated with pulsed anodic oxidation. The laser structure was grown by molecular beam epitaxy (MBE) system. The output powers up to 50 mW per facet in CW mode were reached at room temperature for the 4 μm stripe lasers. The threshold current density of 300 A/cm2 was achieved with 600 μm cavity length. The emission wavelength at 100 mA was 1.19 μm. The slope efficiency was 0.45 W/A in linear output region of light-current characteristics. The laser characteristic temperature was 129 K (20°C–100°C).

Large post-growth energy band-gap tuning of the 980 nm high power laser diode structures

Post-growth energy band gap turning of the 980nm high power semiconductor laser structure through the quantum well intermixing (QWI) has been investigated. The QWI was carried out by depositing a thin film of SiO2 on top surface of the laser structure samples and followed by high temperature annealing. By using the QWI technique, band gap energy of the 980nm quantum well structure has been blue shifted up to >220nm. High quality of the laser diode structure after the QWI has been confirmed by fabricating the high performance semiconductor lasers using the wafer after the QWI.

ZnO film preparation by reactive sputtering method

In this paper, ZnO films were deposited on GaAs (100) substrate as the protective-coating and antireflection coating of semiconductor laser facets, in order to improve the lifetime and reliability. This study investigated the microstructure of ZnO films deposited on GaAs (100) substrate with different sputtering conditions containing RF power, pressure, etc. The optical thickness(nm) of ZnO films was λ/4=96nm, the transmittance was up to 90% at the wavelength of 808nm, and the refractive index n is 1.9. The surface morphology of ZnO films was uniform and smooth; it may be desirable for semiconductor facet film application.

High power 808 nm InGaAlAs semiconductor lasers by MBE

High power 808 nm semiconductor lasers become more and more important for pumping solid-state lasers, medical applications and for material processing such as welding, cutting, or surface treatment. In this paper, Indium has successfully been incorporated into AlGaAs quantum well structures such that the resulting quaternary (InAlGaAs) strained-layer lasers operate in the region of 808 nm. Such lasers were proposed as potentially more robust alternatives to AlGaAs lasers, based on expectations of the lifetime improvements. The suppression of the propagation of <100> dark-line defects (DLDS) in the InAlGaAs devices. Another improvement of lower thresholds has been realized for the devices.

MBE grown LD arrays with non-absorption window for high peak power output

A new nonabsorbing window laser, grown by an interrupted MBE method, has been designed to improve peak power output properties of BA lasers. 5-stack arrays with 2/spl times/0.5 mm/sup 2/ have reached a peak power of 300 W.