Embodiments include a first set of fins having an emitter of a bipolar junction transistor (BJT) disposed over the first set of fins, a second set of fins having a base of the BJT disposed over the second set of fins, and a third set of fins having a collector of the BJT disposed over the third set of fins. A first gate structure is disposed over the first set of fins adjacent to the emitter. A second gate structure is disposed over the second set of fins adjacent to the base. A third gate structure is disposed over the third set of fins adjacent to the collector. The first gate structure, second gate structure, and third gate structure are physically and electrically separated.

A semiconductor device and a manufacturing method thereof are provided. The semiconductor device includes a substrate, a first well, a second well and doped regions. The substrate has heavily doped and lightly doped regions over the heavily doped region. The first wells are disposed in the lightly doped region and arranged as an array. The first wells have a conductive type opposite to a conductive type of the heavily doped and lightly doped regions. The second well is disposed in the substrate over the lightly doped region, and has an active region defined by an isolation structure. The first wells are overlapped with the second well. Top ends of the first wells are lower than a bottom end of the second well. The doped regions are separately located in the active region, and have a conductive type opposite to a conductive type of the second well.

An amplifier overload power limit circuit, system, and a method thereof comprising a monitoring of a current gain of a BJT based on a current detector and limiting power to the BJT based on the monitored current gain to prevent the BJT from driven into a saturation mode and the amplifier overdrive.

Aspects of the disclosure provide an integrated circuit (IC) structure with a bipolar transistor stack within a substrate. The bipolar transistor stack may include: a collector, a base on the collector, and an emitter on a first portion of the base. A horizontal width of the emitter is less than a horizontal width of the base, and an upper surface of the emitter is substantially coplanar with an upper surface of the substrate. An extrinsic base structure is on a second portion of the base of the bipolar transistor stack, and horizontally adjacent the emitter. The extrinsic base structure includes an upper surface above the upper surface of the substrate.

The present disclosure provides a semiconductor structure and a manufacturing method thereof. In the manufacturing method, a first P-type semiconductor layer is provided, and an N-type semiconductor layer and a second P-type semiconductor layer are formed in sequence on the first P-type semiconductor layer. The first P-type semiconductor layer, the N-type semiconductor layer and the second P-type semiconductor layer all include a GaN-based material. When the first P-type semiconductor layer is provided, its upper surface is controlled to be a Ga surface; when the N-type semiconductor layer is formed, its upper surface is controlled to be an N surface; when the second P-type semiconductor layer is formed, its upper surface is controlled to be an N surface. By use of the directivity of wet etching, etching is started from the N surface of the second P-type semiconductor layer and automatically stopped on the Ga surface of the first P-type semiconductor layer 12, thereby avoiding over-etching of the first P-type semiconductor layer and decreased hole carrier concentration. Afterwards, dry etching is performed on the second P-type semiconductor layer and stopped on the upper surface of the N-type semiconductor layer, thus helping to reduce a contact resistance of an electrical connection structure of the N-type semiconductor layer.

A device including a transistor is fabricated by forming a first part of a first region of the transistor through the implantation of dopants through a first opening. The second region of the transistor is then formed in the first opening by epitaxy.

A semiconductor device includes a substrate; a collector including a buried layer within the substrate, a first well region over a first portion of the buried layer, and a first conductivity region at least partially within the first well region; a base including a second well region over a second portion of the buried layer and laterally adjacent to the first well region, and a second conductivity region at least partially within the second well region; an emitter including a third conductivity region at least partially within the second conductivity region; an isolation element between the first and the third conductivity regions; a conductive plate on the isolation element and electrically connected with the first conductivity region. The buried layer, the first well region, the first and the third conductivity regions have a first conductivity type; the second well region and the second conductivity region have a second conductivity type.

An amplifier overload power limit circuit, system, and a method thereof comprising a monitoring of a current gain of a BJT based on a current detector and limiting power to the BJT based on the monitored current gain to prevent the BJT from driven into a saturation mode and the amplifier overdrive.

A semiconductor device include a first semiconductor layer with a first doping concentration. A second semiconductor layer has a second doping concentration and has a first surface and a second opposing surface. The second doping concentration is higher than the first doping concentration. The first surface of the second semiconductor layer is in contact with the first semiconductor layer. A contact is on the second surface of the second semiconductor layer. The contact includes a metal and a semiconductor.

Embodiments include a first set of fins having an emitter of a bipolar junction transistor (BJT) disposed over the first set of fins, a second set of fins having a base of the BJT disposed over the second set of fins, and a third set of fins having a collector of the BJT disposed over the third set of fins. A first gate structure is disposed over the first set of fins adjacent to the emitter. A second gate structure is disposed over the second set of fins adjacent to the base. A third gate structure is disposed over the third set of fins adjacent to the collector. The first gate structure, second gate structure, and third gate structure are physically and electrically separated.