A heterojunction bipolar transistor includes: a substrate; a base mesa disposed on the substrate, wherein the base mesa includes a collector layer and a base layer disposed on the collector layer, and wherein in a top view, the base layer includes a first edge and a second edge opposite to the first edge; an emitter layer disposed on the base layer; a base electrode disposed on the substrate and connected to the base layer; a dielectric layer disposed on the base electrode, wherein a first via hole is formed in the dielectric layer at the first edge of the base layer, and a second via hole is formed in the dielectric layer at the second edge of the base layer; and a conductive feature disposed on the dielectric layer, wherein the conductive feature is connected to the base electrode through the first via hole and the second via hole.

Aspects of the disclosure provide a bipolar transistor structure with a sub-collector on a substrate, a first collector region on a first portion of the sub-collector, a trench isolation (TI) on a second portion of the sub-collector and adjacent the first collector region, and a second collector region on a third portion of the sub-collector and adjacent the TI. A base on first collector region and a portion of the TI. An emitter is on a first portion of the base above the first collector region. The base includes a second portion horizontally displaced from the emitter in a first horizontal direction, and horizontally displaced from the second collector region in a second horizontal direction orthogonal to the first horizontal direction.

A semiconductor device that includes a bipolar transistor, wherein a third opening, through which a pillar bump and a second wiring line, which is electrically connected to an emitter layer, contact each other, is shifted in a longitudinal direction of the emitter layer away from a position at which the third opening would be directly above the emitter layer. The third opening is arranged, with respect to the emitter layer, such that an end portion of the emitter layer in the longitudinal direction of the emitter layer and the edge of the opening of the third opening are substantially aligned with each other.

Aspects generally relate to a heterojunction bipolar transistor (HBT), and method of manufacturing the same. The HBT including an emitter a first, a first side of a base coupled to a second side of the emitter opposite the first side of the emitter. A collector coupled to the base on a second side of the base opposite the emitter, wherein an area of a junction between the base and the collector is less than or equal to an area of a junction between the base and the emitter. A dielectric coupled to the collector. A first conductive base contact coupled to the base and adjacent to the collector and extending over a base-collector junction, the conductive base contact operative as a field plate.

A compound semiconductor device comprises a heterojunction bipolar transistor including a plurality of unit transistors, a capacitor electrically connected between a RF input wire and a base wire for each unit transistor of the unit transistors, and a bump electrically connected to emitters of the unit transistors. The unit transistors are arranged in a first direction. The bump is disposed above the emitters of the unit transistors while extending in the first direction. The transistors include first and second unit transistors, the respective emitters of the first and second unit transistors being disposed on first and second sides, respectively, of a second direction, perpendicular to the first direction, with respect to a center line of the bump extending in the first direction. The capacitor is not covered by the bump, and respective lengths of the respective base wires connected respectively to the first and second unit transistors are different.

A semiconductor device and a method of making a semiconductor device. The device includes an emitter. The device also includes a collector. The device further includes a base stack. The base is located between the emitter and the collector. The base stack includes an intrinsic base region. The device further includes a base electrode. The base electrode comprises a silicide. The silicide of the base electrode may be in direct contact with the base stack. The device may be a heterojunction bipolar transistor.

Aspects of the disclosure provide a bipolar transistor structure with an elevated extrinsic base, and related methods to form the same. A bipolar transistor according to the disclosure may include a collector on a substrate, and a base film on the collector. The base film includes a crystalline region on the collector and a non-crystalline region adjacent the crystalline region. An emitter is on a first portion of the crystalline region of the base film. An elevated extrinsic base is on a second portion of the crystalline region of the base film, and adjacent the emitter.

A power amplifier module includes a substrate including, in an upper surface of the substrate, an active region and an element isolation region. The power amplifier module further includes a collector layer, a base layer, and an emitter layer that are stacked on the active region; an interlayer insulating film that covers the collector layer, the base layer, and the emitter layer; a pad that is thermally coupled to the element isolation region; and an emitter bump that is disposed on the interlayer insulating film, electrically connected to the emitter layer through a via hole provided in the interlayer insulating film, and electrically connected to the pad. In plan view, the emitter bump partially overlaps an emitter region which is a region of the emitter layer and through which an emitter current flows.

An electronic or optoelectronic device includes: (1) a layer of a first material; and (2) a layer of a second material disposed on the layer of the first material, wherein the first material is different from the second material, and the layer of the first material is spaced from the layer of the second material by a gap.

A method of forming a bipolar transistor with a vertical collector contact requires providing a transistor comprising a plurality of epitaxial semiconductor layers on a first substrate, and providing a host substrate. A metal collector contact is patterned on the top surface of the host substrate, and the plurality of epitaxial semiconductor layers is transferred from the first substrate onto the metal collector contact on the host substrate. The first substrate is suitably the growth substrate for the plurality of epitaxial semiconductor layers. The host substrate preferably has a higher thermal conductivity than does the first substrate, which improves the heat dissipation characteristics of the transistor and allows it to operate at higher power densities. A plurality of transistors may be transferred onto a common host substrate to form a multi-finger transistor.