D. Gazula

High Q (33 000) all-epitaxial microcavity for quantum dot vertical-cavity surface-emitting lasers and quantum light sources

Data are presented on the modal and lasing characteristics of a new type of vertical-cavity surface-emitting laser that uses an intracavity mesa to confine the optical mode, with the mesa also confining the quantum dot active region. The quantum dot active region is lithographically isolated within the intracavity mesa using etching and epitaxial regrowth to form an all-epitaxial microcavity light source. Cavity quality factors as high as 33 000 are measured, and ground state lasing is demonstrated with a single quantum dot active layer for temperatures up to ∼110K.

Lens-shaped all-epitaxial quantum dot microcavity

Data are presented on a new type of microcavity that uses epitaxial overgrowth to localize self-organized quantum dots in a microcavity optical mode. The all-epitaxial design eliminates free surfaces from the active material, eliminates quantum dots from the mirror and passive cavity regions, and provides a mechanically robust design with high thermal conductivity. The epitaxial overgrowth leads to a new type of lens-shaped microcavity, while the mesa confinement leads to lithographically defined placement of the quantum dots near the center of the optical mode.

Buried all-epitaxial microcavity for cavity-QED with quantum dots

Optical characterization of a novel type of semiconductor microcavity based on a fully-buried, all-epitaxial design reveals many properties essential for a manufacturable technology. We demonstrate detailed mode-imaging, lasing, as well as a sizeable Purcell effect.

Inert gas maintenance for molecular-beam epitaxy systems

Molecular-beam epitaxy (MBE) most often involves the use of highly toxic and combustible materials, which may subject maintenance personnel to increased health risks. In our efforts to reduce these hazards, we describe the use of inert gas maintenance equipment and procedures that can be employed during the opening of MBE growth chambers. Our operations involve the use of nitrogen-purged glovebags that are sealed over the open port of the growth chamber, wherein applicable tasks are performed through appropriate gloveports of the glovebag. We also describe the associated equipment utilized inside of the glovebags, which aid in the removal of the substrate manipulator and effusion cells. The benefits of reducing the exposure of air to the growth chamber are observed after a bakeout of 145h, wherein the AsO partial pressure within the growth chamber was a factor of 10 lower due to our inert gas maintenance procedures than without. The use of these glovebags allows us to both terminate our bakeout approximat...

All-Epitaxial Quantum Dot Microcavities for VCSELs and Single Photon Sources

Summary form only given. Self-organized quantum dots (QDs) offer unique opportunities to realize new types of semiconductor lasers and spontaneous light sources. One of the more interesting and potentially important is their use in microcavities. In this paper the authors describe experimental data based on incorporating self-organized QDs in a new type of all-epitaxial microcavity that can form a buried heterostructure vertical-cavity surface-emitting laser (VCSEL), and a special type of self-centered single QD microcavity light source

Fabrication of all-epitaxial semiconductor laser using selective interface fermi-level pinning

All epitaxial fully planarized GaAs based semiconductor lasers are demonstrated using a selective Fermi-level pinning at a heterointerface. The results show that this method provides efficient self-aligned current- and mode-confinement and mode controllability by intracavity patterning.

Intracavity grating-confined all-epitaxial vertical-cavity surface-emitting laser based on selective interface Fermi-level pinning

An all-epitaxial GaAs-based vertical-cavity surface-emitting laser is demonstrated with an intracavity mode and current-confining grating. The grating uses selective Fermi-level pinning at a heterointerface to confine the current to the same regions as the optical mode. Despite the grating’s “coarseness,” an increase of efficiency is obtained in side-by-side comparison with devices that lack the grating.

Growth of self-assembled InAs quantum dots for InP-based heterostructures

There has been great technological interest in the use of InAs quantum dots for InP-based lasers which can provide long wavelength emission in the 1.55-2 μm range. The atom-like densities of states of quantum dots provide low threshold current density, high differential gain, temperature insensitive operation and low chirp. However, to take advantage of these aspects, it is important to have dots with uniform size and shape. We report the atomic force microscope (AFM) and photoluminescence (PL) studies of self organized InAs quantum dots grown by molecular beam epitaxy on InGaAs and InAlAs lattice matched to InP. Our experiments confirm prior results that InAs forms quantum wires on InGaAs matrix layer. However, we find that depositing a thin buffer layer of InAlAs helps in the formation of well-shaped quantum dots. We believe that the aluminum in the buffer layer reduces the surface diffusion of indium adatoms and aids the formation of dots with high density. Our results show that formation of quantum dots depends strongly on the strain, surface energy and surface diffusion kinetics that are in turn dependent on the nature of buffer layer and growth conditions. We improve the quality of dots by optimizing the growth parameters such as growth temperature and arsenic overpressure.