By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.

Light Emitting Device

The two-dimensional (2-D) quantum-well (QW) laser diode simulator Minilase-II is presented in detail. This simulator contains a complete treatment of carrier dynamics including bulk transport, quantum carrier capture, spectral hole burning, and quantum carrier heating. The models used in the simulator and their connectivity are first presented. Then the simulator is used to demonstrate the effects of various nonlinear processes occurring in QW lasers. Finally, modulation responses produced by Minilase-II are compared directly with experimental data, showing good quantitative agreement.

Simulation of carrier transport and nonlinearities in quantum-well laser diodes

A conductive element with a lateral oxidation barrier is provided for the control of lateral oxidation processes in semiconductor devices such as lasers, vertical cavity surface emitting lasers and light emitting diodes. The oxidation barrier is formed through modification of one or more layers which initially were receptive to oxidation. The quality of material directly below the oxidation barrier may be preserved. Related applications include the formation of vertical cavity surface emitting lasers on non-GaAs substrates and on GaAs substrates.

Conductive element with lateral oxidation barrier

A method of forming a semiconductor device includes the following steps: providing a plurality of semiconductor layers; providing means for coupling signals to and/or from layers of the device; providing a quantum well disposed between adjacent layers of the device; and providing a layer of quantum dots disposed in one of the adjacent layers, and spaced from the quantum well, whereby carriers can tunnel in either direction between the quantum well and the quantum dots.

Semiconductor devices and methods

The present invention provides a highly compact vertical cavity surface emitting laser structure formed by a lateral oxidation process. Specifically, the present invention allows for the use of well-controlled oxidized regions to bound and to define the aperture of a laser structure in a current controlling oxidation layer, wherein the aperture comprises a conductive region in the oxidation layer. These oxidized regions are formed by the use of a pre-defined bounding pattern of cavities etched in the laser structure, which allow the embedded oxidation layer to be oxidized, and which results in a highly reproducible and manufacturable process.

Highly compact vertical cavity surface emitting lasers

High‐performance planar ‘‘buried‐mesa’’ index‐guided AlGaAs‐GaAs quantum well heterostructure (QWH) lasers have been fabricated by oxidation (H2O vapor+N2 carrier gas, 425–525 °C) of a significant thickness of the high composition AlxGa1−xAs upper confining layer (outside the active stripe). The oxide provides excellent current confinement for low‐threshold laser operation and a low refractive index (n∼1.6) for transverse optical confinement and index guiding. Laser diodes with ∼4 μm‐wide active regions exhibit 300 K continuous (cw) laser thresholds of 8 mA, with single longitudinal mode operation to 23 mW/facet, and maximum output powers of 45 mW/facet (uncoated). Devices fabricated on a lower confinement AlxGa1−xAs‐GaAs QWH crystal (x≲0.6 instead of x≳0.8) with ∼4 μm‐wide active stripes exhibit 300 K cw thresholds of 9 mA and total external differential quantum efficiencies of 66%. Peak output powers ≳80 mW/facet (uncoated) with linear L‐I characteristics over the entire operating range are observed. In...

High‐performance planar native‐oxide buried‐mesa index‐guided AlGaAs‐GaAs quantum well heterostructure lasers

Data are presented on the continuous‐wave (cw) room‐temperature (300 K) operation of multiple stripe AlxGa1−xAs‐GaAs quantum well heterostructure (QWH) laser arrays defined with native oxide contact masking. Use of the native AlxGa1−xAs(x≳0.7) oxide allows the fabrication of high‐performance devices without depositing foreign oxide or dielectric layers (SiO2 or Si3N4). Arrays of ten 5‐μm‐wide emitters on 7 μm centers are coupled and operate at powers as high as 300 mW per facet, or at wider stripe spacing (5 μm emitters on 10 μm centers) as high as 400 mW per facet. These data indicate that current blocking layers of native oxide, formed from AlxGa1−xAs with H2O vapor in N2 carrier gas (400 °C, 3 h), can be used in the construction of high‐power multiple stripe QWH arrays with excellent performance characteristics.

Native‐oxide‐defined coupled‐stripe AlxGa1−xAs‐GaAs quantum well heterostructure lasers

Impurity‐induced layer disordering (IILD) along with oxidation (native oxide) of high‐gap AlxGa1−xAs confining layers is employed to fabricate low‐threshold stripe‐geometry buried‐heterostructure AlxGa1−xAs‐GaAs quantum well heterostructure (QWH) lasers. Silicon IILD is used to intermix the quantum well and waveguide regions with the surrounding confining layers (beyond the laser stripe) to provide optical and current confinement in the QW region of the stripe. The high‐gap AlxGa1−xAs upper confining layer is oxidized in a self‐aligned configuration defined by the contact stripe and reduces IILD leakage currents at the crystal surface and diffused shunt junctions. AlxGa1−xAs‐GaAs QWH lasers fabricated by this method have continuous 300 K threshold currents as low as 5 mA and powers ≳ 3l mW/facet for ∼ 3‐μm‐wide active regions.

Low‐threshold disorder‐defined native‐oxide delineated buried‐heterostructure AlxGa1−xAs‐GaAs quantum well lasers

Native‐oxide planar AlxGa1−xAs‐GaAs quantum well heterostructure ring laser diodes (25‐μm‐ wide annulus, 250‐μm inside diameter, 300‐μm outside diameter) are demonstrated. The curved cavities (full‐ring, half‐ring, and quarter‐ring) are defined by native oxidation (H2O vapor+N2 carrier gas, 450 °C) of the entire upper confining layer inside and outside of the annulus. The native oxide provides current confinement and a sufficiently large lateral index step, and thus photon confinement, to support laser oscillation along the ring. Half‐ring laser diodes fabricated in a self‐aligned geometry exhibit continuous wave (cw) 300‐K thresholds as low as ∼105 mA (∼500‐μm circular cavity length), high total external differential quantum efficiencies (∼49%), and cw output powers of ≳40 mW.

Planar native‐oxide AlxGa1−xAs‐GaAs quantum well heterostructure ring laser diodes

Data are presented showing that the native oxide that can be formed on high Al composition AlxGa1−xAs (x≳0.7) confining layers on AlyGa1−yAs‐AlzGa1−zAs (y≳z) superlattices or quantum well heterostructures serves as an effective mask against impurity diffusion (Zn or Si), and thus against impurity‐induced layer disordering. The high quality native oxide is produced by the conversion of high Al composition AlxGa1−xAs (x≳0.7) confining layers, which can be grown on a variety of heterostructures, via H2O vapor oxidation (≳400 °C) in an N2 carrier gas.

S. C. Smith

Papers

High‐performance planar native‐oxide buried‐mesa index‐guided AlGaAs‐GaAs quantum well heterostructure lasers

Native‐oxide‐defined coupled‐stripe AlxGa1−xAs‐GaAs quantum well heterostructure lasers

Low‐threshold disorder‐defined native‐oxide delineated buried‐heterostructure AlxGa1−xAs‐GaAs quantum well lasers

Planar native‐oxide AlxGa1−xAs‐GaAs quantum well heterostructure ring laser diodes

Native‐oxide masked impurity‐induced layer disordering of AlxGa1−xAs quantum well heterostructures