A vertical high-blocking III-V bipolar transistor, which includes an emitter, a base and a collector. The emitter has a highly doped emitter semiconductor contact region of a first conductivity type and a first lattice constant. The base has a low-doped base semiconductor region of a second conductivity type and the first lattice constant. The collector has a layered low-doped collector semiconductor region of the first conductivity type with a layer thickness greater than 10 μm and the first lattice constant. The collector has a layered highly doped collector semiconductor contact region of the first conductivity type. A first metallic connecting contact layer is formed in regions being integrally connected to the emitter. A second metallic connecting contact layer is formed in regions being integrally connected to the base. A third metallic connecting contact region is formed at least in regions being arranged beneath the collector.

In one example, a sensor includes a heterojunction bipolar transistor and component sensing surface coupled to the heterojunction bipolar transistor via an extended base component. In another example, a biosensor for detecting a target analyte includes a heterojunction bipolar transistor and a sensing surface. The heterojunction bipolar transistor includes a semiconductor emitter including an emitter electrode for connecting to an emitter voltage, a semiconductor collector including a collector electrode for connecting to a collector voltage, and a semiconductor base positioned between the semiconductor emitter and the semiconductor collector. The sensing surface is coupled to the semiconductor base of the heterojunction bipolar transistor via an extended base component and includes a conducting film and a reference electrode.

On a single-crystal semiconductor substrate with an upper surface including a first direction in which an inverted mesa step extends and a second direction in which a forward mesa step extends in response to anisotropic etching in which an etching rate depends on crystal plane orientation, a bipolar transistor including a collector layer, a base layer, and an emitter layer that are epitaxially grown, and a base wire connected to the base layer are arranged. A step is provided at an edge of the base layer, and the base wire is extended from inside to outside of the base layer in a direction intersecting the first direction in a plan view. An intersection of the edge of the base layer and the base wire has a disconnection prevention structure that makes it difficult for step-caused disconnection of the base wire to occur.

A heterojunction bipolar transistor includes a collector layer, a base layer, an emitter layer, and a semiconductor layer that are laminated in this order, wherein the emitter layer includes a first region having an upper surface on which the semiconductor layer is laminated, and a second region being adjacent to the first region and having an upper surface that is exposed, and the first and second regions of the emitter layer have higher doping concentrations in portions near the upper surfaces than in portions near an interface between the emitter layer and the base layer.

Structures for a bipolar junction transistor and methods of forming a structure for a bipolar junction transistor. The structure includes an emitter having a raised portion, a collector having a raised portion, and a base having a base layer and an extrinsic base layer stacked with the base layer. The base layer and the extrinsic base layer are positioned in a lateral direction between the raised portion of the emitter and the raised portion of the collector, the base layer has a first width in the lateral direction, the extrinsic base layer has a second width in the lateral direction, and the second width is greater than the first width.

Various embodiments of the present disclosure are directed towards a method for forming a bipolar junction transistor (BJT). A dielectric film is deposited over a substrate and comprises a lower dielectric layer, an upper dielectric layer, and an intermediate dielectric layer between the lower and upper dielectric layers. A first semiconductor layer is deposited over the dielectric film and is subsequently patterned to form an opening exposing the dielectric film. A first etch is performed into the upper dielectric layer through the opening to extend the opening to the intermediate dielectric layer. Further, the first etch stops on the intermediate dielectric layer and laterally undercuts the first semiconductor layer. Additional etches are performed to extend the opening to the substrate. A lower base structure and an emitter are formed stacked in and filling the opening, and the first semiconductor layer is patterned to form an upper base structure.

A bipolar junction transistor is provided with an emitter structure that is positioned above the upper surface of the base region. The thickness of the emitter and the interfacial oxide thickness between the emitter and the base is configured to optimize a gain for a given type of transistor. A method of fabricating PNP and NPN transistors on the same substrate using a complementary bipolar fabrication process is provided. The method enables the emitter structure for the NPN transistor to be defined separately to that of the PNP transistor. This is achieved by epitaxially growing the emitter layer for the PNP transistor and growing the emitter layer for the NPN transistor in a thermal furnace.

A heterojunction bipolar transistor includes a collector layer, a base layer, and an emitter layer that are stacked on a substrate. The collector layer includes a graded semiconductor layer in which an electron affinity increases from a side closer to the base layer toward a side farther from the base layer. An electron affinity of the base layer at an interface closer to the collector layer is equal to an electron affinity of the graded semiconductor layer at an interface closer to the base layer.

A first sub-collector layer functions as an inflow path of a collector current that flows in a collector layer of a heterojunction bipolar transistor. A collector ballast resistor layer having a lower doping concentration than the first sub-collector layer is disposed between the collector layer and the first sub-collector layer.

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.