International Business Machines Corporation

US Government as Represented by the Secretary of the Army

USA as Represented by Secretary of the Navy

Leroy L Chang

Leo Esaki

Chin-An Chang

George A Sai-Halasz

Emilio E Mendez

Hiro Munekata

Hideo Ohno

Stephan vonMolnar

Supratik Guha

Frank F Fang

Raphael Tsu

Ulrich Strom

Hiroo Munekata

John J Quinn

Wen-I Wang

The present invention is a hetero superlattice pn junction. In particular, the invention combines n and p type superlattices into a single pn junction having a bandgap sufficient to create high frequency (i.e. blue or higher) light emission. Individual superlattices are formed using a molecular beam epitaxy process. This process creates thin layers of well material separated by thin layers of barrier material. The well material is doped to create carrier concentrations and the barrier materials are chosen in combination with the thickness of the well materials to adjust the effective bandgap of the superlattice in order to create an effective wide bandgap material. The barrier material for the n and p type superlattices is different from the material used to form either of the two types of well layers. A particular embodiment of the present invention forms a first superlattice from n type doped ZnSe well layers and undoped ZnMnSe barrier layers and forms a second superlattice from p type doped ZnTe well layers and undoped ZnMnSe barrier layers. The first and second superlattices are merged into a hetero superlattice pn junction. The thickness and composition of the individual well and barrier layers can be modified to adjust the effective bandgap of the pn junction. Therefore, a wide bandgap diode is formed from previously incompatible materials.

Hetero-superlattice PN junctions

A new semiconductor material or compound and method for its manufacture is disclosed. The material or compound has the Formula III-V or IV which includes as part of the compound, a transition element or a rare earth element present in an amount sufficient to change the material or compound from a paramagnetic state to a locally ordered magnetic state. The material or compound is made by depositing III, and V or IV and a transition element or a rare earth element onto a substrate at conditions such that the transition element or rare earth element that is deposited on the substrate is not in equilibrium with the material or compound. By employing this technique new semiconductor materials or compounds can be made including Ga.sub.1-x Mn.sub.x As and In.sub.1-x Mn As where Mn is present in an amount greater than about 5.4.times.10.sup.20 cm.sup.-3.

Class of magnetic materials for solid state devices

A new semiconductor material or compound and method for its manufacture is disclosed. The material or compound has the Formula III-V or IV which includes as part of the compound, a transition element or a rare earth element present in an amount sufficient to change the material or compound from a paramagnetic state to a locally ordered magnetic state. The material or compound is made by depositing III, and V or IV and a transition element or a rare earth element onto a substrate at conditions such that the transition element or rare earth element that is deposited on the substrate is not in equilibrium with the material or compound. By employing this technique new semiconductor materials or compounds can be made including Ga.sub.1-x Mn.sub.x As and In.sub.1-x Mn.sub.x As where Mn is present in an amount greater than about 5.4.times.10.sup.20 cm.sup.-3.

The mobility of carriers in the channel region of a field effect transistor can be increased by providing a layered structure wherein electrons are separated from impurities. The channel is made up of external layers of wide bandgap material and internal layers with a narrower bandgap where the bottom of the conduction band of one layer is below the top of the valence band of the adjacent layer. A structure is shown with a layered channel having AlSb external layers and at least one or both of InAs and GaSb internal layers.

Field effect transistor

A semiconductor superlattice is provided with a one-dimensional quantum pipeline type carrier path. The pipeline is formed at the intersection of different energy level layers of the superlattice. Conductivity modulation through an adjacent exposed surface is employed for control in the pipeline and in arrays thereof. The pipeline carrier path involves both electrons and holes. A structure of Ga.sub.1-x Al.sub.x As with alternating 100.ANG. and 500.ANG. thick layers of different x has positioned, intersecting those layers, a 100.ANG. thick GaAs layer covered by a GaAlAs layer. Control and contacting electrodes are positioned on the exposed surfaces.

One-dimensional quantum pipeline type carrier path semiconductor devices

A field-effect transistor includes a conduction channel between a source terminal and a drain terminal, which channel employs holes as the charge carriers. The conduction channel is disposed within a layer of material comprising a group III-V compound of the periodic table and having a crystalline lattice structure which is stressed in two dimensions by means of epitaxial growth upon a thicker and rigid supporting layer comprising a different group III-V compound having a larger lattice spacing. The layer having the conduction channel is relatively thin being on the order of a few electron wavelength in thickness. The stretching of the layer having the conduction channel shift the energy levels of holes therein to remove the degenerate state thereof, thereby elevating light holes to an energy level characterized by increased mobility.

Semiconductor device with hole conduction via strained lattice

A semiconductor structure is provided with progressively changing band gap in a plurality of stages each at an abrupt interface with an asymmetry in the band gap widths such that the major difference in energy gap discontinuity is in the band favoring a particular type of carrier. The transition regions between the progressive material sections are smaller than the carrier mean free path so as to provide kinetic energy for efficient carrier multiplication with reduced noise as the carriers traverse through the device.

Photomultiplier

Misfit dislocation density at an InAs-GaAs interface is reduced in both InAs-GaSb and In.sub.1-x Ga.sub.x As-GaSb.sub.1-y As.sub.y superlattices grown on GaAs substrates by means of an MBE (molecular beam epitaxy) growth technique consisting of a step graded sequence of composition layers between substrate and superlattice whose composition changes in discrete concentration steps from the composition of the substrate to the composition of the superlattice.

MBE Growth technique for matching superlattices grown on GaAs substrates

FET With heterojunction induced channel

Misfit dislocation density at an InAs-GaAs interface is reduced in both I-GaSb and In.sub.1-x Ga.sub.x As-GaSb.sub.1-y As.sub.y superlattices grown on GaAs substrates by means of a MBE (molecular beam epitaxy) growth technique consisting of a step graded sequence of composition layers between substrate and superlattice whose composition changes in discrete concentration steps from the composition of the substrate to the composition of the superlattice.

MBE growth technique for matching superlattices grown on GaAs substrates

An ultrasonic wave generator comprising a semiconductor superlattice with a periodic variation in its space charge and a far infrared laser for applying a transient electric field to the superlattice transverse to the direction of its periodic variation. The ultrasonic wave produced has a wavelength of the period of the superlattice which can result in 100 gigahertz ultrasonic waves. Structure is included for guiding these waves into an acoustic system.

Superlattice ultrasonic wave generator

A superlattice structure is disclosed in which alternating layers of semiductor alloy materials provide a one dimensional spatial periodic variation in band edge energy. A first layer of the superlattice device is an alloy including a first Group III material and a first Group V material, preferably In As, while the second layer is an alloy including a second Group III material different from the first Group III material and a second Group V material different from the first Group V material, and preferably GaSb. In the superlattice structure the valence band of the second alloy is closer to the conduction band of the first alloy than it is to the valence band of the first alloy.

Heterojunction superlattice with potential well depth greater than half

A system and method including the use of hydrogen in the molecular beam evaporation process for epitaxy growth, such as in the formation of GaAs and GaAlAs and Sn for n-type dopant impurity. In a molecular beam epitaxy system, a hydrogen beam introduced and, along with the molecular beam, is directed on the substrate during the epitaxy growth such that the presence of the relatively small volume of hydrogen influences the physical surface properties of the epitaxially grown material and therefore the quality of the epitaxy.

Molecular-beam epitaxy system and method including hydrogen treatment

A heterojunction structure made of two semiconductor layers is disclosed in hich light is applied to the structure and absorbed, and the emission of light from the structure is controlled by an electric field applied perpendicularly to the planes of the layers. It is further disclosed that the device can be employed as a selective light filter or modulator.

Controlled absorption in heterojunction structures

An optical device is disclosed which includes first and second superlattice emiconductor regions. The first superlattice semiconductor region includes a plurality of alternating barrier and light absorbing layers which absorbs light of a first light frequency. The second superlattice region also includes a plurality of alternating barrier and light absorbing layers. However, the light absorbing layers of the second superlattice semiconductor region absorbs light of a different frequency.

Growing community of inventors

Goldens Bridge, NY, United States of America

Leroy L Chang