A heterojunction bipolar transistor includes a substrate, a semiconductor unit, an electrode unit and a dielectric layer. The semiconductor unit includes a collector layer, a base layer and an emitter layer sequentially formed on the substrate in such order. The electrode unit includes a collector electrode, a base electrode, and an emitter electrode respectively disposed on the collector layer, the base layer and the emitter layer. The dielectric layer covers and cooperates with the emitter layer to define an opening extending therethrough and terminating at the base layer to expose a contact region. The base electrode is disposed on the contact region, extends through the opening, and partially covers the dielectric layer.

Strain is used to enhance the properties of p- and n-materials so as to improve the performance of III-N electronic and optoelectronic devices. In one example, transistor devices include a channel aligned along uniaxially strained or relaxed directions of the III-nitride material in the channel. Strain is introduced using buffer layers or source and drain regions of different composition.

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.

Techniques are disclosed for forming a heterojunction bipolar transistor (HBT) that includes a laterally grown epitaxial (LEO) base layer that is disposed between corresponding emitter and collector layers. Laterally growing the base layer of the HBT improves electrical and physical contact between electrical contacts to associated portions of the HBT device (e.g., a collector). By improving the quality of electrical and physical contact between a layer of an HBT device and corresponding electrical contacts, integrated circuits using HBTs are better able to operate at gigahertz frequency switching rates used for modern wireless communications.

A method for forming a heterojunction bipolar transistor is provided. The method includes (a) forming a doped region in a group IV semiconductor layer of a substrate; (b) forming an epitaxially grown III-V semiconductor body on a surface portion of the doped region, the body extending from the surface portion and protruding vertically above the doped region, wherein the doped region and the body forms a first sub-collector part and a second sub-collector part, respectively; and (c) forming an epitaxially grown III-V semiconductor layer stack on the body, the layer stack comprising a collector, a base and an emitter. There is further provided a heterojunction bipolar transistor device.

A semiconductor device having metamorphic high electron mobility transistor (HEMT)-heterojunction bipolar transistor (HBT) integration on a semiconductor substrate. An example semiconductor device generally includes a semiconductor substrate, a bipolar junction transistor (BJT) disposed above the semiconductor substrate and comprising indium, and a HEMT disposed above the semiconductor substrate and comprising indium.

The invention provides a structure of an emitter layer and a base layer that reduces the influence of a conduction band energy barrier generated at an interface between the emitter layer and the base layer on power amplifier characteristics for a GaAs HBT using InGaAs grown by pseudomorphic growth in the base layer. In the first invention, InGaP having a CuPt-type ordering is used in the emitter layer. In the second invention, a p-type impurity concentration of an InGaAs base layer grown by pseudomorphic growth is less in an emitter layer side portion than in a collector layer side portion.

This disclosure provides a high-voltage terahertz strained SiGe/InGaP heterojunction bipolar transistor and a preparation method thereof. An InGaP material has characteristics of a high carrier mobility of the InP material and a forbidden band width of the GaP material, so that the present disclosure employs the N-type In.sub.1-xGa.sub.xP layer as the collector to improve the frequency and power characteristics of the device, and realize the system integration of terahertz band chips. Further, the present disclosure utilizes the characteristics of the above materials and takes an advantages of “energy band engineering”, uses the In.sub.1-xGa.sub.xP (x=0-1) is used as the material of the collector of the SiGe-HBT, the composition molar ratio X of In and Ga is appropriately selected, such that the materials SiGe of the collector and the sub-collector have the same lattice constant, so as to effectively improve interface characteristics of InGaP and SiGe materials.

The present disclosure relates to semiconductor structures and, more particularly, to heterojunction bipolar transistors and methods of manufacture. The structure includes: a sub-collector region in a substrate; a collector region above the sub-collector region, the collector region composed of semiconductor material; an intrinsic base region composed of intrinsic base material surrounded by the semiconductor material above the collector region; and an emitter region above the intrinsic base region.

An emitter contact layer, an emitter layer, a base layer, a p-type base layer, a collector layer, and a sub-collector layer are crystal-grown over a first substrate in this order with the main surface as the Group III polar surface. The emitter contact layer includes a nitride semiconductor that is made n-type at a relatively high concentration. The emitter layer includes a nitride semiconductor having a bandgap larger than that of the nitride semiconductor constituting the emitter contact layer. The base layer includes an undoped nitride semiconductor having a bandgap smaller than that of the nitride semiconductor constituting the emitter layer. The p-type base layer includes the same nitride semiconductor as the base layer and made p-type.