A semiconductor device having a GeSiSn base region combined with an emitter region and a collector region can be used to fabricate a bipolar transistor or a heterojunction bipolar transistor. The GeSiSn base region can be compositionally graded or latticed matched or strained to GaAs. The GeSiSn base region can be wafer bonded to a GaN or SiC collector region.

Cubic BAs is used in semiconductors to improve the thermal characteristics of a device. The BAs is used in device layers to improve thermal conductivity. The BAs also provides thermal expansion characteristics that are compatible with other semiconductors and thereby further improves reliability. The substrates of the semiconductors may also include vias that contain BAs. The BAs in the vias may contact the BAs in the device layers. Some vias may have a surface area to volume ratio of greater than 10 to better assist with device heat dissipation.

In an aspect, a heterojunction bipolar transistor (HBT) includes a sub-collector disposed on a collector. The collector has a collector contact disposed on the sub-collector and located on a first side of the heterojunction bipolar transistor. The HBT includes an emitter disposed on an emitter cap. The emitter has an emitter contact disposed on the emitter cap and located on a second side of the heterojunction bipolar transistor. The HBT includes a base having a base contact located on the second side of the heterojunction bipolar transistor.

A method for manufacturing an optical device includes providing a carrier waver, provide a first substrate having a first surface region, and forming a first gallium and nitrogen containing epitaxial material overlying the first surface region. The first epitaxial material includes a first release material overlying the first substrate. The method also includes patterning the first epitaxial material to form a plurality of first dice arranged in an array; forming a first interface region overlying the first epitaxial material; bonding the first interface region of at least a fraction of the plurality of first dice to the carrier wafer to form bonded structures; releasing the bonded structures to transfer a first plurality of dice to the carrier wafer, the first plurality of dice transferred to the carrier wafer forming mesa regions on the carrier wafer; and forming an optical waveguide in each of the mesa regions, the optical waveguide configured as a cavity to form a laser diode of the electromagnetic radiation.

A heterojunction bipolar transistor includes a first emitter electrode, a second emitter electrode, and a third emitter electrode that are formed on an emitter cap layer. The first emitter electrode has an area greater than or equal to an area of the emitter cap layer in a plan view, and is made of a tungsten alloy. The second emitter electrode is formed on the first emitter electrode, is made of a metal that contains W and is different from a metal of the first emitter electrode, and has an area greater than an area of the first emitter electrode in a plan view.

Provided is a semiconductor epitaxial wafer, including a substrate, a first epitaxial structure, a first ohmic contact layer and a second epitaxial stack structure. It is characterized in that the ohmic contact layer includes a compound with low nitrogen content, and the ohmic contact layer does not induce significant stress during the crystal growth process. Accordingly, the second epitaxial stack structure formed on the ohmic contact layer can have good epitaxial quality, thereby providing a high-quality semiconductor epitaxial wafer for fabricating a GaAs integrated circuit or a InP integrated circuit. At the same time, the ohmic contact properties of ohmic contact layers are not affected, and the reactants generated during each dry etching process are reduced.

A bipolar transistor including a first collector layer, a second collector layer, a base layer, and an emitter layer is disposed on a substrate. Etching characteristics of the second collector layer are different from etching characteristics of the first collector layer and the base layer. In plan view, an edge of an interface between the first collector layer and the second collector layer is disposed inside an edge of a lower surface of the base layer, and an edge of an upper surface of the second collector layer coincides with the edge of the lower surface of the base layer or is disposed inside the edge of the lower surface of the base layer.

A vertical bipolar junction transistor may include an intrinsic base epitaxially grown on a first emitter or collector, the intrinsic base being compositionally graded, a second collector or emitter formed on the intrinsic base, and an extrinsic base formed all-around the intrinsic base. The extrinsic base may be isolated from the first emitter or collector by a first spacer. The extrinsic base may be isolated from the second collector or emitter by a second spacer. The extrinsic base may have a larger bandgap than the intrinsic base. The intrinsic base may be doped with a p-type dopant, and the first emitter or collector, and the second collector or emitter may be doped with an n-type dopant. The first emitter or collector, the intrinsic base, and the second collector or emitter may be made of a III-V semiconductor material.

A circuit element is formed on a substrate made of a compound semiconductor. A bonding pad is disposed on the circuit element so as to at least partially overlap the circuit element. The bonding pad includes a first metal film and a second metal film formed on the first metal film. A metal material of the second metal film has a higher Young's modulus than a metal material of the first metal film.

The present disclosure relates to semiconductor structures and, more particularly, to a heterojunction bipolar transistor and methods of manufacture. The structure includes: a sub-collector region; a collector region above the sub-collector region; an intrinsic base region composed of intrinsic base material located above the collector region; an emitter located above and separated from the intrinsic base material; and a raised extrinsic base having a stepped configuration and separated from and self-aligned to the emitter.