M. Ilegems

Room-temperature operation of low-threshold separate-confinement heterostructure injection laser with distributed feedback

Separate‐confinement heterostructure injection lasers with periodic corrugations in the optical cavity were prepared by a hybrid liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) growth process. The N‐Al0.3Ga0.7As, N‐Al0.12Ga0.88As, p‐GaAs active layer, and P‐Al0.12Ga0.88As layers were grown by LPE, a 0.3748‐μm periodic corrugation was ion milled into the P‐Al0.12Ga0.88As layer, and then the P‐Al0.3Ga0.7As and p‐GaAs top layers were grown over the corrugation by MBE. The temperature dependence of the lasing wavelength between 12.6 and 24.8 °C demonstrated the behavior expected for a distributed‐feedback laser. The threshold current density was 2.2 kA/cm2 at room temperature.

Vapor epitaxy of gallium nitride

Abstract The epitaxial growth of GaN by vapor phase reaction between GaCl and NH 3 in a He carrier gas ancient is described. Single crystal layers 100–200 ωm thick and ∼ 1 cm 2 in area, were obtained on (0001) oriented sapphire substrates at deposition temperatures near 1050 °C. The best undoped layers grown had carrier concentrations of 1–2 × 10 17 cm −3 with electron mobilities near 400 cm 2 /V sec at 300 K.

Selective area growth of GaAs/AlxGa1−xAs multilayer structures with molecular beam epitaxy using Si shadow masks

Selective growth of patterned GaAs and AlxGa1−xAs thin‐film structures with well‐defined optically smooth mirrorlike edges has been achieved with a Si‐mask shadowing technique for molecular beam epitaxy. Single and multilayer stripe‐mesa waveguides with widths as narrow as 1 μm, two‐dimensional waveguide tapers, and various other epilayer patterns have been fabricated using single‐level or multilevel masking. This technique has potential for use in the realization of integrated optoelectronic circuits in the GaAs/AlxGa1−xAs system.

Optical birefringence of thin GaAs‐AlAs multilayer films

The measured birefringence of the refractive indices of GaAs‐AlAs multilayers grown by molecular beam epitaxy is found to vary from 0.056 at 0.9 μm to 0.042 at 1.1 μm.

Phase‐matched second harmonic generation in a periodic GaAs waveguide

Using a tunable laser operating near 2 μm, second harmonic generation was observed in a GaAs waveguide having a grating etched in one interface. Phase matching occurs when β2−2β1−ϑ=0, where ϑ=2π/Λ is the wave vector of the grating of period Λ and β1 and β2 are the fundamental and harmonic wave vectors.

Phase diagram of the system Al-Ga-P

Abstract Liquidus isotherms at 800, 900, 1000 and 1100 °C and corresponding solidus isotherms at 1000 and 1100 °C have been determined in the Ga-rich region of the Al-Ga-P phase diagram. The experimental results can be accurately described by a thermodynamic model in which the AlP-GaP solid solution is assumed to be ideal and the ternary liquid is treated as a simple solution.

Epitaxial growth on optical gratings for distributed feedback GaAs injection lasers

Abstract Good quality epitaxial overgrowth of Al 0.3 Ga 0.7 As on corrugated GaAs and Al 0.12 Ga 0.88 As surfaces has been achieved by molecular-beam epitaxy. The electrical properties of the interface appear to be equivalent to those prepared by LPE without growth interruption. The corrugations were third order Bragg gratings of ∼0.37 μm period and ∼0.20 μm depth and were formed by ion milling. Separate confinement heterostructure injection lasers with these periodic corrugations in the optical cavity have demonstrated lasing behavior characteristic of distributed feedback. They have operated with room-temperature threshold current densities as low as 2.2 kA/cm 2 . These results suggest that the MBE overgrowth is a useful technique for the fabrication of integrated optoelectronic structures which include active devices.

Interference filters: single crystal multilayer AlAs–GaAs

High and low reflectance single crystal quarter wave stacks consisting of alternating layers of AlAs and GaAs have been grown on GaAs substrates by molecular beam epitaxy.

Second harmonic generation in a thin AlAs‐GaAs multilayer structure with wave propagation in the plane of the layers

Second harmonic generation was measured from a thin AlAs‐GaAs single‐crystal multilayer using a laser tunable from 1.9 to 2.2 μm as fundamental. Due to propagation effects in the multilayers, the index mismatch nTM(2ω)−nTE(ω), obtained from the coherence length oscillations, is smaller than for the corresponding alloy.