Xerox Corporation

Eic Corporation

Wj Communications, Inc.

Clarence John Dunnrowicz

David P Bour

Linda T Romano

Yan Chen

Hin Fai Chau

Chien Ping Lee

Michael A Kneissl

Decai Sun

Ross D Bringans

Nanlei Larry Wang

Barry Jia-Fu Lin

Daniel Hofstetter

The safe-operating area (SOA) in a heterojunction bipolar transistor (HBT) is improved by providing a collector region in the transistor having a graded (uniformly or stepped) doping between the base region and the underlying subcollector region with the collector doping being lower near the base and higher near the subcollector and with the collector doping being less than the doping of the subcollector. The non-uniformly doped collector reduces Kirk effect induced breakdown when collector current increases.

Heterojunction bipolar transistor having non-uniformly doped collector for improved safe-operating area

The safe operating area (SOA) in a heterojunction bipolar transistor is improved by inserting a material between the collector and subcollector of the transistor with the insertion layer being a material having a wider energy bandgap than the material of the collector. The insertion layer increases the breakdown field at the collector-subcollector junction and thereby increases the Kirk effect induced breakdown voltage.

Heterojunction bipolar transistor having wide bandgap material in collector

Group III-V nitride films are fabricated on mesas patterned either on substrates such as sapphire substrates, or on mesas patterned on group III-V nitride layers grown on substrates. The mesas provide reduced area surfaces for epitaxially growing group III-V nitride films, to reduce thermal film stresses in the films to reduce cracking. The surfaces of the mesas on which the films are grown are dimensioned and oriented to reduce the number of thin film crack planes that can grow on the mesas. Further cracking reduction in the films can be achieved by thinning the substrate to form membranes. The reduced substrate thickness at the membranes reduces the thermal expansion mismatch tensile stress in the films. The mesas can reduce or eliminate the occurrence of cracks in GaN or AlGaN epitaxial films grown on the mesas, for percentages of aluminum in the AlGaN films of up to about 18%. The improved group III-V nitride films can be used in optoelectronic devices including LEDs and edge and surface emitting laser diodes.

Fabrication of group III-V nitrides on mesas

This invention relates to a multiple wavelength laser structure, and more particularly, to a multiple wavelength laser array structure fabricated by flip-chip bonding from laser structures on two different substrates. A side by side red/IR laser structure is flip-chip bonded to a blue laser structure to form a red/blue/IR hybrid integrated laser structure.

Multiple wavelength laser arrays by flip-chip bonding

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Santa Cruz, CA, United States of America

Clarence John Dunnrowicz