J. P. Duchemin

Some characteristics of the GaAs/GaAlAs graded‐index separate‐confinement heterostructure quantum well laser structure

We describe the characteristics of graded‐index separate‐confinement heterostructure (GRIN‐SCH) quantum well laser structures for a wide range of quantum well thickness and graded layer composition. It was deduced that the ‘‘GRIN’’ region enhances carrier confinement and assists the thermalization of carriers into the quantum well. A maximum value of T0 of 190 K was measured for these single quantum well lasers.

1.2–1.6 μm GaxIn1−xAsyP1−y-InP DH lasers grown by LPMOCVD

Abstract Room temperature pulse operation and continuous wave (CW) operation in the 1.2–1.6 μm region have been achieved in GaInAsP-InP DH lasers fabricated on material grown by LPMOCVD. Threshold currents density as low as 430 A/cm 2 (cavity length of 950 μm) have been measured for devices emitting at 1.3 μm. Threshold current densities of 1060 A/cm 2 (cavity length of 400 μm) have been obtained for devices emitting at 1.55 μm, with active layer thicknesses of 0.22 μm. Values of T 0 between 60 and 70 K have been obtained. Fundamental transverse mode oscillation has been achieved (for CW operation) up to an output power of 10 mW. The preliminary results on the aging test are most encouraging and demonstrate that the LPMOCVD lasers emitting at 1.2–1.6 μm have comparable degradation rates to those of LPE lasers suggesting the LPMOCVD technique is promising for large scale production of laser diodes.

First observation of the quantum Hall effect in a Ga0.47In0.53As‐InP heterostructure with three electric subbands

Shubnikov–de Haas and quantum Hall effects have been studied in GaInAs‐InP heterojunctions grown by modified low pressure metalorganic chemical vapor deposition. In contrast to the results reported up till now on GaInAs‐InP heterojunctions with nearly the same channel electron density, not one but three electric subbands, E0, E1, and E2, are occupied in zero magnetic field. Two electric subbands E0 and E1 contribute to the quantum Hall effect. Magnetic depopulation of the higher (E1 and E2) subbands is observed in both perpendicular and tilted magnetic field orientations. This enables a demonstration of the importance of intersubband scattering in resistivity and cyclotron resonance.

Two‐dimensional electron gases in quantum well and superlattices of Ga0.25In0.75As0.50P0.50/InP heterostructures grown by low pressure metalorganic chemical vapor deposition

We report the first observation of a two‐dimensional electron gas from Shubnikov–de Haas experiments, in a Ga0.25In0.75As0.50P0.50‐InP heterojunction, multi‐quantum well, and superlattices grown by metalorganic chemical vapor deposition at reduced pressure.

Very low threshold buried ridge structure lasers emitting at 1.3 μm grown by low pressure metalorganic chemical vapor deposition

GaInAsP‐InP buried ridge structure lasers emitting at 1.3 μm have been fabricated on material grown completely by low pressure metalorganic chemical vapor deposition. These lasers have low threshold (11 mA), exhibit linear (kink‐free) light‐current characteristics up to high powers (10 mW/facets), and can be operated at high temperatures (70 °C). Excellent uniformity over 10 cm2 has been obtained, and an external quantum efficiency of 60% for two faces has been measured.

cw operation of 1.57‐μm GaxIn1−xAsyP1−yInP distributed feedback lasers grown by low‐pressure metalorganic chemical vapor deposition

Continuous wave operation of 1.57‐μm distributed feedback lasers fabricated on material grown by two‐step low‐pressure metalorganic chemical vapor deposition growth process is reported for the first time. Room‐temperature continuous wave threshold currents as low as 60 mA have been measured for devices with cavity length of 300 μm and stripe width of 5 μm. Single longitudinal mode operation at fixed mode was obtained under the continuous wave condition, in the temperature range 9–90 °C, with the wavelength shift of 0.9 A/°C. A stop band of 25 A in which no resonance mode emission existed, was observed in the output spectrum of the distributed feedback laser.

Abrupt OMVPE grown GaAs/GaAlAs heterojunctions

In this paper, we describe the growth of abrupt heterojunctions and very thin GaAs and GaAlAs layers for use in quantum well lasers or TEGFET (two-dimensional electron-gas field effect transistors) structures. SIMS measurements have been performed which confirm that the growth rate measured for thick layers (1 to 10 μm) can be used to estimate the thickness of very thin layers (<100 A) with a good accuracy. Luminescence data from GaAlAs/GaAs/GaAlAs quantum wells shows that there is probably some random compositional fluctuation in the GaAlAs quantum well barrier layers which leads to a broadening of the luminescence peak and a shift to lower energy. These quantum wells form the active layer of separate confinement heterostructure (SCH) and graded refractive index (GRIN) SCH quantum well laser structures. We will review the results of our study of these lasers explaining the separate roles of the GRIN and quantum well. New results will be given showing how the value of T0 can be improved by increasing, the number of quantum wells in the active layer.

cw phase‐locked array Ga0.25In0.75As0.5P0.5‐InP high power semiconductor laser grown by low‐pressure metalorganic chemical vapor deposition

Continuous and pulsed phase‐locked operation of a high power GaInAsP‐InP semiconductor laser emitting at 1.3 μm has been achieved. The laser consists of a seven‐striped array of ridge‐island lasers fabricated by a two‐step low‐pressure metalorganic chemical vapor deposition growth technique. Linear output powers greater than 300 mW (pulsed) and 120 mW (cw) have been obtained with no facet coatings. The far‐field full widths at half power, both parallel and perpendicular to the junction plane, were 3° and 45°, respectively, at 10 mW (at 20 °C) which is evidence for strong stripe‐to‐stripe coupling.

Selected area growth of InP by low pressure metalorganic chemical vapor deposition on ion implanted InP substrates

InP deposition by metalorganic chemical vapor deposition on implanted substrates has different qualities according to the damage density of the substrate surface induced by the bombardment. For low damage densities, the layer deposited is monocrystalline. For middle damage densities, the deposition is composed of nuclei. For high damage densities, there is no deposition on the implanted surface, and in this case, we observe a material transport. By using the ion implantation technique in conjuntion with metalorganic chemical vapor deposition, it is possible to have selective area growth of InP.

Bulk and transfer doping effects in AlxGa1−xAs layers grown on semi‐insulating GaAs substrates

The observation of both bulk and two‐dimensional conduction is reported in GaAlAs layers grown by metalorganic chemical vapor deposition on undoped semi‐insulating GaAs substrates. The electron concentrations were determined from Shubnikov–de Haas periodicities in different magnetic field configurations. Bulk conduction is found to dominate at 4.2 K only after illumination with above band‐gap light. This is interpreted as due to spatial transfer of some carriers with the GaAlAs layer.