At&t Bell Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

Other

John C Bean

Sergey Luryi

John Milo Poate

Leonard C Feldman

Anthony Thomas Fiory

Gregg S Higashi

Thomas P Pearsall

Kin-Chung R Chiu

Abbas Ourmazd

Clifford Alan King

Henryk Temkin

Joe C Campbell

Roosevelt People

Boris Gelmont

Tatiana Globus

George Arthur Rozgonyi

David L Windt

Justin Larry Peticolas

Bahram Jalali-Farahani

David V Lang

Alexander Kastalsky

Lloyd Harriott

Robert Hull

Pineas Paxton Marshall

Naser Alijabbari

A photovoltaic structure for absorption from the solar spectrum, includes a light transmitting substrate layer, a transparent electrode layer on the substrate layer, a direct band-gap, wide band-gap, nanocrystalline or microcrystalline, think film semiconducting first layer on the transparent electrode layer, a second think film layer comprising a narrow band-gap semiconductor on the first layer a second electrode layer on the second think film layer, and a protective layer on the second electrode layer. The structure has a hetero-structure at the boundary between the wide-band-gap layer and the second thin film layer. The second layer can be chalcogenide salt having an average thickness of 0.4 to 1.2 &#x3bc;m, and preferably an average thickness of 0.5 to 0.6 &#x3bc;m. The chalcogenide salt layer is a lead chalcogenide, such as a nanocrystaline lead sulfide, nanocrystalline lead selenide, or a nanocrystalline lead telluride.

Thin film photovoltaic cell system and method of manufacture

We have found a way to, e.g., substantially increase the number of layers in a pseudomorphic strained layer semiconductor mirror over the number obtainable in an analogous conventional mirror, making it possible to obtain pseudomorphic strained layer mirrors of increased reflectance. Such a pseudomorphic mirror consists of alternating layers of a first and a second semiconductor material (e.g., Ge.sub.x Si.sub.1-x /Si), of thickness t.sub.1 and t.sub.2, and refractive index n.sub.1 and n.sub.2, respectively, with the number of layer pairs chosen such that the mirror thickness is less than or equal to the 'critical thickness' L.sub.c. For thicknesses &gt;L.sub.c the mirror will contain dislocations. An article according to the invention comprises a mirror whose layer thicknesses are chosen such that n.sub.1 t.sub.1 .noteq.n.sub.2 t.sub.2, with n.sub.1 t.sub.1 +n.sub.2 t.sub.2 =p.lambda./2, (p being an odd integer, typically 1). In other words, the optical thickness of the layers is not the conventional p.lambda./4. The thicknesses are also chosen such that the average lattice mismatch between substrate and mirror is reduced, compared to the analogous conventional (.lambda./4) mirror. Mirrors according to the invention can be advantageously used in optoelectronic devices such as surface emitting lasers and p-i-n photodetectors.

Article comprising an epitaxial multilayer mirror

A method of producing patterned epitaxial silicon films and devices fabricated thereby is described. The method forms a first layer of a refractory material on a substrate and pattern delineates the first layer. Silicon is then deposited at a temperature within the range between 400 degrees C. and 700 degrees C. and the polycrystalline material that forms is removed.

Method of fabricating patterned epitaxial silicon films utilizing

The inventive method of making a poly-Si emitter transistor (PET) comprises opening an emitter window in a dielectric (typically SiO.sub.2) layer, and depositing onto the thus exposed surface and/or into the single crystal Si material that underlies the exposed surface at least one atomic species. This deposition step is following by the conventional poly-Si deposition, dopant implantation and 'drive-in'. In a currently preferred embodiment the novel deposition step comprises a low dose, low energy As implantation (5.times.10.sup.13 -2.times.10.sup.15 atoms/cm.sup.2, 0.1-5 keV). The novel method can result in significantly improved device characteristics, e.g., in a doubling of h.sub.FE, as compared to analogous prior art PETs.

Method of making a polysilicon emitter bipolar transistor

Disclosed are strained layer heteroepitaxial structures (e.g., GeSi/Si) that can have low threading dislocation density as well as a substantially planar surface. Furthermore, a large fraction (e.g., &gt;90%) of the total surface are of the structure can be available for device processing. These advantageous features are achieved through utilization of novel 'dislocation sinks' on or in the substrate whose height parameter h is less than or about equal to the thickness of the strained heteroepitaxial layer on the substrate. Exemplarily, h.gtoreq.h.sub.c, where h.sub.c is the critical thickness associated with misfit dislocation generation in the substrate/overlayer combination.

Article comprising a lattice-mismatched semiconductor heterostructure

An ordered-disordered transition is observed in semiconductor alloys which enables either the ordered or disordered structure to be produced.

Method of controlling the order-disorder state in a semiconductor device

A molecular beam epitaxy method of growing Ge.sub.x Si.sub.1-x films on silicon substrate is described. Semiconductor heterostructures using Ge.sub.x Si.sub.1-x layers grown on either Ge or Si substrates are described.

Semiconductor heterostructures having Ge.sub.x Si.sub.1-x layers on Si

A strained layer superlattice comprising Ge.sub.x Si.sub.1-x layers interleaved with Si layers is an excellent photodetector at infrared wavelengths due to the large shift in bandgap caused by the strain in the superlattice.

Device having strain induced region of altered bandgap

A photodetector, comprising a Ge.sub.x Si.sub.1-x superlattice region between two silicon cladding layers in which the Ge.sub.x Si.sub.1-x layers absorb light, is described.

Silicon germanium photodetector

Apparatus is described which is especially well suited for simultaneous molecular beam epitaxy of materials, such as silicon, on a plurality of substrates.

Apparatus for simultaneous molecular beam deposition on a plurality of

Device using ordered semiconductor alloy

Described is a method for producing semiconductor heterostructures incorporating a metal layer. The metal layer, typically a metal-silicide, can be produced by, e.g., co-deposition or reaction with the substrate. The resulting silicide is typically epitaxial and of high crystalline perfection.

Method for producing metal silicide-silicon heterostructures

A molecular beam epitaxy method of growing Ge.sub.x Si.sub.1-x films on silicon substrate is described.

Method for epitaxially growing Ge.sub.x Si.sub.1-x layers on Si

Devices useful, for example, as detectors in telecommunications systems have been formed utilizing a specific structure. In particular, a p-i-n device is fabricated on a silicon substrate having the necessary circuitry for signal processing. This p-i-n device is produced by depositing an intermediary region having a compositional gradient on this substrate and forming a germanium based p-i-n diode on the intermediary region.

Germanium p-i-n photodetector on silicon substrate

Described are semiconductor heterostructures incorporating a metal layer. Devices based on the heterostructures are described, as are techniques for preparing the heterostructures. Specific embodiments wherein the metal layer is a metal silicide are detailed, and hot electron devices using this structure are analyzed briefly.

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New Providence, NJ, United States of America

John C Bean