Northrop Grumman Systems Corporation

Trw Limited

Augusto L Gutierrez-Aitken

Donald James Sawdai

Dwight C Streit

Aaron K Oki

Patrick T Chin

Eric N Kaneshiro

Edward A Rezek

Michael Wojtowicz

Thomas R Block

Tsung-Pei Chin

Frank M Yamada

Gregory Scott Leslie

A double heterojunction bipolar transistor structure having desirable properties of a low base-emitter turn-on voltage and no electron blocking discontinuities in the base-collector junction. These properties are achieved by selecting base, emitter and collector materials to provide a bandgap profile that exhibits abrupt transitions at the heterojunctions, such that both abrupt transitions are due to transitions in the valence band edge of the bandgap, but not in the conductive band edge of the bandgap.

Low turn-on voltage, non-electron blocking double HBT structure

A heterojunction bipolar transistor (HBT) device structure is provided which facilitates the reduction of the base-collector capacitance and a method for making the same. The base-collector capacitance is decreased by fabricating a base micro-bridge connecting a base contact to a base mesa on the HBT. The base micro-bridge is oriented along about one of 001, 010, 00{overscore (1)}, and 0{overscore (1)}0 direction to a major flat of the wafer. The HBT device employs a phosphorous based collector material. During removal of the phosphorous based collector material, the base layer is undercut forming the micro-bridge, successfully removing the collector and sub-collector material below the bridge due to the orientation of the micro-bridge. The removal of collector and sub-collector material reduces the base-collector junction area, and therefore reduce the base-collector junction capacitance.

Double HBT base metal micro-bridge

A preferred embodiment of the present invention provides a Schottky diode formed from a conductive anode contact, a semiconductor junction layer supporting the conductive contact and a base layer ring formed around at least a portion of the conductive anode contact. In particular, the base layer ring has material removed to form layer material gap (e.g., a vacuum gap) adjacent to the conductive anode contact. A dielectric layer is also provided to form one boundary of the base layer material gap.

Low leakage schottky diode

A heterojunction bipolar transistor is doped in the sub-collector layer ( ) with phosphorus ( ). The presence of the phosphorus causes any interstitial gallium ( ) to be bonded ( ) to the phosphorus ( ) and move to a lattice site. The result is that the interstitial gallium does not diffuse to the base layer and thus does not cause the beryllium to be displaced and diffused. Instead of doping with phosphorus, a layer including phosphorus can also be utilized.

Interstitial diffusion barrier

Reduction in the base to collector capacitance of a heterojunction bipolar transistor, and, improved high frequency performance is achieved using existing materials and processes by undercutting the collector ( ) under the base ( ) along two parallel sides of the base mesa ( &mdash;FIG. ), and providing a sloped collector edge ( &mdash;FIG. ) along the remaining two parallel sides of the base. The foregoing is accomplished by selective etching and with the four sides of the mesa regions oriented as a non-rectangular parallelogram ( &mdash;FIG. ) in which one pair of sides is in parallel with one of the said &lsqb; &rsqb; and &lsqb; {overscore (1)}&rsqb; planes of the crystalline structure and the other pair of sides in parallel with one of the &lsqb; &rsqb; and &lsqb; {overscore (1)} {overscore (1)}&rsqb; planes of the crystalline structure.

Ultra high speed heterojunction bipolar transistor having a cantilevered base

A preferred embodiment of the present invention provides a Schottky diode ( ) formed from a conductive anode contact ( ), a semiconductor junction layer ( ) supporting the conductive contact ( ) and a base layer ring ( ) formed around at least a portion of the conductive anode contact ( ). In particular, the base layer ring ( ) has material removed to form a base layer material gap ( ) (e.g., a vacuum gap) adjacent to the conductive anode contact ( ). A dielectric layer ( ) is also provided to form one boundary of the base layer material gap ( ).

Low leakage Schottky diode

A low dark current photodiode and a method for reducing dark current in a photodiode. A preferred embodiment of the present invention provides a photodiode comprising a barrier layer. The barrier layer comprises a barrier layer material having a wider band-gap than the band-gap of the absorption layer material of the photodiode. The barrier layer comprises sublayers, which are doped to position the high-electric field region at the pn junction of the photodiode in the barrier layer. The method for reducing dark current in a photodiode comprises building a barrier layer into the structure of a photodiode. Building the barrier layer comprises building a layer of semiconductor material with wider band-gap than the i-layer material. Building the barrier layer preferably further comprises doping the barrier layer material to position the high-energy region at the pn junction of the photodiode in the barrier layer, thus reducing dark current.

Low dark current photodiode

An optical semiconductor device ( ) includes an optical semiconductor structure ( ) and a light reflector ( ) monolithic with the optical semiconductor structure ( ). The light reflector ( ) is disposed to direct light to and/or from the optical semiconductor structure ( ).

Monolithic light reflector

The invention relates to an integrated circuit structure that includes a substrate wafer having an active device layer disposed on a surface of the substrate wafer and having an electrically conductive element contained therein. The integrated circuit structure further comprises a barrier disposed between the substrate wafer and the active device layer, where the barrier blocks carriers injected into the substrate wafer and reduces low frequency oscillation effect.

Integrated circuit structure having a charge injection barrier

The performance of a heterojunction bipolar transistor (HBT) operating at high power is limited by the power that can be dissipated by the device. This, in turn, is limited by the thermal resistance of the device to heat dissipation. In a typical HBT, and especially InP-based HBTs, heat generated during operation is concentrated near the collector-base junction. In order to more efficiently dissipate heat downward through the device to the substrate, both the collector and the sub-collector are formed of InP, which has a substantially lower thermal resistance than other typically used semiconductor materials.

Heterojunction bipolar transistor with reduced thermal resistance

A photodiode for an input light signal comprising an absorption layer having an absorption coefficient which is less than the absorption coefficient of InGaAs when measured at a wavelength of 1.55 &mgr;m. First and a second cladding layer are disposed on opposite sides of the absorption layer leaving exposed a side of the absorption layer. Positively and negatively polarized contact layers are disposed on the first and second cladding layers respectively. The input light signal is directed into the exposed side of the absorption layer and the absorption layer absorbs the input light signal and photo-generates therefrom carriers. The contact layers collect the carriers and generate therefrom photocurrent.

High power waveguide photodiode with an absorption layer with reduced absorption coefficient

A photodetector having improved responsivity includes first, second and third contact layers and first and second absorption layers. The first and second absorption layers are disposed on opposite sides of the first contact layer. The second contact layer is disposed on the first absorption layer and the third contact layer is disposed on the second absorption layer. The first contact layer has a first polarity. The second and third contact layers have a second polarity which is opposite the first polarity. Preferably, the first and second absorption layers are each made of a material having approximately equivalent electrical characteristics and the second and third contact layers are interconnected. Alternatively, one absorption layer is responsive to a first wavelength and another absorption layer is responsive to a second wavelength.

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Redondo Beach, CA, United States of America

Augusto L Gutierrez-Aitken