Xerox Corporation

Amoco Corporation

Spectra Diode Laboratories, Inc.

Robert D Burnham

Donald R Scifres

William Streifer

Robert L Thornton

Thomas L Paoli

Nick Holonyak, Jr

Robert Arthur Sprague

Eric G Rawson

Ricardo S Sussmann

Noble Marshall Johnson

Henry W Sang, Jr

Edward T Maas, Jr

John E Epler

Harlan Forrest Chung

Peter Cross

Thomas Wolfram

Bruce A Vojak

Nick Holonvak, Jr

Hsing Kung

A heat sink for a semiconductor component of a heat-dissipating and light-radiating semiconductor electronic device. Diamond particles are embedded in a metal matrix to form a composite having a coefficient of thermal expansion which is substantially that of the semiconductor component of the electronic device.

Diamond composite heat sink for use with semiconductor devices

A composite comprised of diamond particles embedded in a metal matrix is a highly satisfactory heat sink material for use with a semiconductor.

An optically pumped laser which includes a laser diode array for generating optically pumped radiation having a uniform intensity distributed over a broad band-width, and a lasant material with an absorption band for receiving radiation within such bandwidth.

Optically pumped laser

A quantum well heterostructure laser has low current density threshold and high T.sub.O values and includes a plurality of contiguous semiconductor layers formed on a substrate wherein one or more the layers form an active region capable of quantization of electron states. The active region is confined by a pair of outer superlattice regions which provide optical confinement and low thermal resistance while preventing the development of antiwaveguiding properties. Many configurations are shown to demonstrate the many forms that the overall laser structure can take and, in particular, the nature of the outer or inner cladding regions of different superlattice geometries and forms.

Quantum well heterostructure lasers with low current density threshold

A window laser having at least one window region with a transparent waveguide layer optically coupled to an active region generating lightwaves. The waveguide layer is characterized by a broader guided transverse mode for the lightwaves than the active region and may have a thickness which is greater than the active region, a refractive index difference with respect to cladding layers which is less than a refractive index difference between the active region and the cladding layers, or both. The waveguide layer may be coupled to the active region via a transition region characterized by a gradual change in the guide mode width of the lightwaves, such as from a tapered increase in thickness of the waveguide layer in a direction away from the active region. The preferred method of making window region having these transparent waveguides is impurity induced disordering, in which the interfaces between active region and cladding layers is disordered by impurity species to produce the waveguide layer with increased bandgap and a graded transverse refractive index profile. The laser is characterized by a high power output beam with reduced far field transverse divergence.

Buried waveguide window regions for improved performance semiconductor

Different diffusion rates can be made operative relative to diffusion disordering in designated areas of a thin active layer or of quantum well feature compared to thermal disordering in other areas thereof where disordering is not desired by the selective placement of migratory defects in a semiconductor support means, such as a semiconductor substrate or semiconductor support layer for supporting subsequently epitaxially deposited semiconductor layers. Such migratory defects as used herein are intended to include impurities and/or other lattice defects initially introduced into the semiconductor support means prior to epitaxial deposition of semiconductor layers constituting the semiconductor structure, wherein at least one of such layers comprises a thin active layer (i.e., a layer with relative higher refractive index compared to the refractive index of at least contiguous epitaxially deposited layers) not necessarily capable of exhibiting quantum size effects or a quantum well feature capable of exhibiting quantum size effects. These migratory defects diffuse or migrate into subsequently grown epitaxial layers providing regions of higher lattice defects in the epigrown layers compared to regions of the same layers where no migratory defects were initially introduced into the semiconductor support means.

Semiconductor structures utilizing semiconductor support means

A high performance III-V heterostructures exhibiting quantum size effects has been achieved in MODCVD utilizing in situ grown (IV).sub.x (III-V).sub.1-x alloys, where (IV) is a group IV element comprising Si, Ge, C or Sn or admixtures thereof and (III-V) is a group III-V binary, trinary, quaternary or pentad compound or alloy such as, for example, GaAs, AlAs, GaAlAs, GaAlAsP, InGaAlP, InAlAsP or InGaAlAsP. Specific examples are (Si.sub.2).sub.x (GaAs).sub.1-x, which is an alloy that functions as a barrier when grown in situ in a GaAs active region of a heterostructure and (Ge.sub.2).sub.x (GaAs).sub.1-x, which is an alloy that functions as a quantum well when grown in situ in GaAs or GaAlAs active region (e.g. highest refractive index and narrowest bandgap) of a heterostructure. The disclosure further relates to the utilization of a nucleating or catalytic process wherein a small amount of a cluster collector or anchorage component, e.g., Al, Mg or Ti, on the surface of the sample in the reaction zone of the MOCVD reactor. This component is believed to function as a nucleating or catalytic site to which IV--IV pairs initially attach and, thereafter, continually attach to form islands that provide three dimensional barriers or wells in an active region of a heterostructure. Another aspect of the disclosure deals with in situ induced disordering vis a vis surface initiated impurity induced disordering (SIIID) as known in the art. Superlattice or well disordering can be achieved in situ during crystal growth rather than by introduction of an impurity component into the superlattice as contemplated in SIIID.

(IV).sub.x (III-V).sub.1-x alloys formed in situ in III-V

The thermalization process is effectively slowed down by reducing the tunneling or communication probability between adjacent quantum wells of a MQW heterostructure laser to increase the number of allowable subbands in the wells and thereby correspondingly increase the range of wavelength tuning of such lasers. This increase of allowable subbands is accomplished by (A) either (1) spatially varying the elemental composition of the wells or barriers or both in order to spatially increase or decrease the energy band from well to well or (2) spatially varying the thickness of the wells or barriers or both in order to spatially increase or decrease the energy band from well to well, or (B) a combination of (1) and (2) of (A).

Wavelength tuning of multiple quantum well (MQW) heterostructure lasers

An optically uncoupled laser array is modified at its current confinement geometry to introduce nonuniformity in effective optical cavity width and/or length among the different lasers comprising the laser array. An array laser comprising a plurality of spaced lasing elements with an optical cavity for generating and propagating radiation under lasing conditions with each of the laser elements being optically uncoupled from one another is enhanced by an extended spectral emission linewidth and reduction in temporal coherence. This extended spectral emission linewidth and reduction in temporal coherence is accomplished by changing the gravity gain or loss for at least a majority of the laser elements relative to each other whereby a different longitudinal mode(s) of operation and frequency of operation exist for each such laser element. The enhancement may be accomplished, for example, by providing nonuniformity in the current confinement width or nonuniformity in the effective current pumped region or a change in optical cavity absorption loss for at least a majority of laser elements. Such nonuniformity or change may be randomly varying or monotonically increasing or decreasing across the laser elements of the array.

Incoherent, optically coupled laser arrays with increased spectral width

A laser in which the central portion is provided with current pumping means consisting of an array of current confining stripe contacts to provide a multiple emitter active layer and the end sections of the laser are provided with transparent waveguides. The active layer of this laser can be abruptly stepped along the direction of light propagation, or provided with tapered end couplers, or in any other way made transparent, so that light escapes from the emitters of the active layer of the central portion of the laser into the transparent waveguides at the ends of the laser. The transparent waveguides are of a non-absorbing material of higher bandgap than the central active layer material, or of the same material but otherwise rendered transparent, so that the escaping light strikes the mirror facets and is reflected back, whereby a portion of the reflected light couples back into its emitter and provides the optical feedback for laser operation. Phase-locking is achieved because when the light from each emitter under each pumped stripe region emerges into the transparent waveguides, there is less or no lateral waveguiding, and therefore the light from each emitter diverges. Because of this divergence, when this light strikes the mirror facets, portions of the light from each emitter are reflected back into other adjacent emitters, thus phase-locking the laser output and making it highly collimated. Relative to conventional multi-emitter lasers, five to ten times higher output powers from the collimated beam are obtained, such increase in power occurring because the material at the laser mirror surface is transparent to the active region radiation and therefore is not damaged by the very intense light.

Phased-locked window lasers

A thin film bilayer composite source comprises a deposited impurity source layer, e.g. Si or Sb, heavily doped with a diffusion enabling agent, e.g. As, and capped with a passivating layer, e.g. Si.sub.3 N.sub.4, SiO.sub.2, AlN or SiO.sub.x N.sub.y. In a preferred embodiment, a thin film bilayer composite source comprises a Si layer on the surface of said structure vapor deposited at a temperature in excess of 500.degree. C. in the presence of a source of As to hevily dope the layer in the range of 5%-20% atomic weight and a thin cap layer of Si.sub.3 N.sub.4 deposited on the Si layer at a temperature in excess of 500.degree. C. having a thickness only sufficient to prevent the outdiffusion of Ga and As, which thickness may be about 400 .ANG.-700 .ANG.. An important aspect of the employment of this bilayer composite source as a diffusion source for III-V structures is that the composite source is initially deposited at high temperatures, above 500.degree.0 C., i.e., at temperatures that are into the range of annealing temperature, e.g. about 500.degree.-900.degree. C., preferably 700.degree.-850.degree. C., so that cracking due to thermal strain or compressive stress will not occur on subsequent high temperature annealing thereby providing reproducible, uniform impurity diffusion into III-V structures. A particular application of bilayer composite source is in impurity induced disordering (IID).

Method of introducing impurity species into a semiconductor structure

A diode laser bar producing a linear array of laser beams without lateral superradiance. The laser bar has a double-heterostructure or quantum well structure. Etched channels in the substrate create lateral corrugations in the subsequently deposited layers including the active region. The corrugations alternate between offset groove and plateau regions in the lateral direction but are straight in the longitudinal light propagating direction. Any laterally propagating light is interrupted at steps, between groove and plateau regions, by deflection, scattering or transmission out of the active region. Interruption may also be achieved with a plurality of parallel etched grooves extending in the longitudinal direction. The grooves which cut through the active region present a semiconductor-air interface for reflection and/or scattering of laterally propagating light out of the active region. Proton bombarded regions may be provided above the step regions in the top layers to channel current and prevent optical burnout of the step regions. A small percentage of laser light may be allowed to laterally propagate into adjacent active regions to promote phase locking across the laser bar.

Lateral superradiance suppressing diode laser bar

A split contact phased array laser comprising a plurality of parallel emitters under phase locked operation and productive of an output beam having a preferred emission wavelength and preferred far field mode of operation. The charge distribution profile in the laser is changed to cause the output beam to deflect and scan in the far field. The improvement in the laser is the provision of at least three independently current pumped segments formed transversely of said emitters wherein at least one of the segments is current pumped above threshold level sufficient to primarily determine the emission wavelength and mode of operation of the laser while the current supplied to the remaining segments is below this level and is varied relative to one another to cause the output beam to deflect and scan in the far field without substantial change to the emission wavelength and mode of operation. This is because the charge density is essentially clamped under the one dominant contact segment and is only minimally influenced by further changes in the pumping current.

Split contact phased array lasers

An incoherent, optically uncoupled laser array for an electro-optic line modulator or a line printer or the like and comprising a plurality of spatial laser emitters characterized by having high power density and a uniform far field emission pattern. Structural means is provided in the array to permit the spacing of the emitters sufficiently close to provide a uniform far field emission pattern without permitting phaselocking between adjacent emitters of the array. The structural means may comprise geometric lateral and diagonal displacement of adjacent optical cavities of the laser elements. Alternatively, the structural means may comprise a plurality of spatially disposed isolation regions extending across the laser array and extending into the laser array a distance sufficient to optically isolate the optical cavities of the laser elements from one another and prevent optical coupling between adjacent laser elements. The spatial isolation regions may be formed into the fabricated laser array using impurity induced disordering (IID).

Incoherent, optically uncoupled laser arrays for electro-optic line

A novel energy beam induced layer disordering (EBILD) process is used to (a) locally melt in a scanned pattern regions of a solid state semiconductor heterostructure to produce an alloy of intermediate composition having different optical properties and/or (b) incorporating significantly large amounts of an impurity, present in an encapsulation surface layer of a solid state semiconductor heterostructure, into regions of the heterostructure via absorption of the impurity into liquid alloy melt to form regions having different optical and/or electrical properties and (c) thereafter optionally applying IID to enlarge or extend the disordered/as-grown boundaries of the initially melted region. As a direct write analogue to surface initiated impurity induced disordering (IID), EBILD is a flexible and viable process with high importance for continuous reproducibility and high yield in the fabrication of optoelectronic devices and thin film electronic and optoelectronic circuitry. Characterized in its simplest terms, the method of impurity incorporation contemplated by this invention provides such incorporation from a solid phase impurity source using an energy beam liquid phase technique to bring about absorption of the impurity with underlying constituents in a desired pattern to produce regions that may be disordered and possess different electrical properties or optical properties or both compared to regions not part of the scanned pattern.

Growing community of inventors

Los Altos Hills, CA, United States of America

Robert D Burnham