Patent Number: 7,687,886

App Number: 11/153,078

Assignee: MicroLink Devices, Inc.

Prior Art Cutoff Date: predating June 14, 2005

Summary: Patent discloses, among other things, an HBT with two collectors with different doping in order to increase on-state breakdown voltage.

Looking for prior art that discloses using a double collector structure with varying doping levels to achieve the breakdown voltages at the current densities shown in Fig. 5 of the patent (Not the Standard InGaP).

1 Answer 1


This might have been anticipated by https://www.google.com/patents/WO2003077284A2 "Heterojunction bipolar transistor having thinned base-collector depletion region" :

"ABSTRACT A heterojunction bipolar transistor includes a substrate (101) that supports an emitter layer (103), a base layer (105) and a collector layer (104). The collector layer is made thin, in combination with a reduction in a base-collector area in order to reduce capacitance, and is made from a wide band gap material that exhibits a high breakdown voltage. Preferably the collector layer is an intrinsic semiconductor material, such as intrinsic InGaP having a thickness of about 90 nm. The collector is thinned to reduce the probability of scattering, enabling electrons to be accelerated to higher kinetic energies due to an electrical field applied to a base-collector depletion region and one present in a base-collector junction."

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