摘要:
Semiconductor devices such as VCSELs, SELs, LEDs, and HBTs are manufactured to have a wide bandgap material near a narrow bandgap material. Electron injection is improved by an intermediate structure positioned between the wide bandgap material and the narrow bandgap material. The intermediate structure is an inflection, such as a plateau, in the ramping of the composition between the wide bandgap material and the narrow bandgap material. The intermediate structure is highly doped and has a composition with a desired low electron affinity. The injection structure can be used on the p-side of a device with a p-doped intermediate structure at high hole affinity.
摘要:
A VCSEL with undoped top mirror. The VCSEL is formed from an epitaxial structure deposited on a substrate, and a periodically doped conduction layer is coupled to the undoped top minor. A periodically doped spacer layer is coupled to an active region. An undoped bottom minor coupled to the periodically doped spacer layer. A first intracavity contact is coupled to the periodically doped conduction layer and a second intracavity contact is coupled to the periodically doped spacer layer.
摘要:
A VCSEL with undoped mirrors. An essentially undoped bottom DBR mirror is formed on a substrate. A periodically doped first conduction layer region is formed on the bottom DBR mirror. The first conduction layer region is heavily doped at a location where the optical electric field is at about a minimum. An active layer, including quantum wells, is on the first conduction layer region. A periodically doped second conduction layer region is connected to the active layer. The second conduction layer region is heavily doped where the optical electric field is at a minimum. An aperture is formed in the epitaxial structure above the quantum wells. A top mirror coupled to the periodically doped second conduction layer region. The top mirror is essentially undoped and formed in a mesa structure. An oxide is formed around the mesa structure to protect the top mirror during wet oxidation processes.
摘要:
Quantum wells and associated barriers layers can be grown to include nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., within the 1260 to 1650 nm range. In accordance with features of the present invention, a vertical cavity surface emitting laser (VCSEL) can include at least one quantum well comprised of InGaAsN; barrier layers sandwiching said at least one quantum well; and confinement layers sandwiching said barrier layers. Confinement and barrier layers can comprise AlGaAs, GaAsN. Barrier layers can also comprise InGaAsN. Quantum wells can also include Sb. Quantum wells can be developed up to and including 50 Å in thickness. Quantum wells can also be developed with a depth of at least 40 meV.
摘要:
Methods and systems produce flattening layers associated with nitrogen-containing quantum wells and prevent 3-D growth of nitrogen containing layers using high As fluxes. MEE (Migration Enhanced Epitaxy) is used to flatten layers and enhance smoothness of quantum well interfaces and to achieve narrowing of the spectrum of light emitted from nitrogen containing quantum wells. MEE is performed by alternately depositing single atomic layers of group III and V before, and/or after, and/or in-between quantum wells. Where GaAs is used, the process can be accomplished by alternately opening and closing Ga and As shutters in an MBE system, while preventing both from being open at the same time. Where nitrogen is used, the system incorporates a mechanical means of preventing nitrogen from entering the MBE processing chamber, such as a gate valve.
摘要:
A single mode VCSEL including a substrate having a lower surface and an upper surface, a bottom electrical contact disposed along the lower surface of the substrate, a lower mirror portion disposed upon the upper surface of the substrate, an active region disposed upon the lower mirror portion, an upper mirror portion disposed upon the active region, an equipotential layer disposed upon the upper mirror portion, an insulating layer interposed between the upper mirror portion and the equipotential layer and adapted to form an aperture therebetween, and an upper contact portion disposed upon the equipotential layer outside the perimeter of the aperture.
摘要:
A system and method for providing a single mode VCSEL (vertical cavity surface emitting laser). A lower mirror is formed on a substrate. An active region including one or more quantum wells is formed over the lower mirror. The upper mirror formed over the active region can include multiple layers and may be formed to be have substantially isotropic conductivity. The layers in the upper mirror can include a lightly doped DBR layer, a heavily doped second layer including an isolation region, and a third heavily doped DBR layer. The active region may include conduction layers, which may be periodically doped, to improve conductivity and reduce free carrier absorption.
摘要:
In order to achieve a long wavelength, 1.3 micron or above, VCSEL or other semiconductor laser, layers of strained quantum well material are supported by mechanical stabilizers which are nearly lattice matched with the GaAs substrate, or lattice mismatched in the opposite direction from the quantum well material; to allow the use of ordinary deposition materials and procedures. By interspersing thin, unstrained layers of e.g. gallium arsenide in the quantum well between the strained layers of e.g. InGaAs, the GaAs layers act as mechanical stabilizers keeping the InGaAs layers thin enough to prevent lattice relaxation of the InGaAs quantum well material. Through selection of the thickness and width of the mechanical stabilizers and strained quantum well layers in the quantum well, 1.3 micron and above wavelength lasing is achieved with use of high efficiency AlGaAs mirrors and standard gallium arsenide substrates.
摘要:
A VCSEL having an N-type Bragg mirror with alternating layers of high bandgap (low index) and low bandgap (high index) layers of AlGaAs. The layers may be separated by a step change of Al composition followed by a graded region, and vice versa for the next layer, in the N-type mirror to result in a lower and more linear series resistance. Also, an N-type spacer layer may be adjacent to an active region of quantum wells. There may be a similar step in a change of Al composition from the nearest layer of the N-type mirror to the N-type spacer formed from a lower bandgap direct AlGaAs layer to provide lower free carrier absorption. With electron affinity engineering, a minority carrier hole barrier may be inserted adjacent to the quantum wells to improve hole confinement at high current density and high temperature.
摘要:
Quantum wells and associated barriers layers can be grown to include nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., within the 1260 to 1650 nm range. In accordance with features of the present invention, a vertical cavity surface emitting laser (VCSEL), can include at least one quantum well comprised of GaAsSb; barrier layers sandwiching said at least one quantum well; and confinement layers sandwiching said barrier layers. Barrier and confinement layers can comprise of AlGaAs. Barrier layers can also be comprised of GaAsP. Nitrogen can be placed in quantum wells. Quantum wells can be developed up to and including 50 Å in thickness. Quantum wells can also be developed with a depth of at least 40 meV.