Abstract: The present disclosure relates to semiconductor structures and, more particularly, to a substrate with trap rich and low resistivity regions and methods of manufacture. The structure includes: a high resistivity semiconductor substrate; an active device over the high resistivity semiconductor substrate; and a low resistivity region floating in the high resistivity semiconductor substrate and which is below the active device.

Abstract: Structures for a varactor diode and methods of forming same. The structure comprises a first semiconductor layer including a section on a substrate, a second semiconductor layer on the section of the first semiconductor layer, a third semiconductor layer on the second semiconductor layer, and a doped region in the section of the first semiconductor layer. The section of the first semiconductor layer and the doped region have a first conductivity type, and the second semiconductor layer comprises silicon-germanium having a second conductivity type opposite to the first conductivity type, and the third semiconductor layer has the second conductivity type. The doped region contains a higher concentration of a dopant of the first conductivity type than the section of the first semiconductor layer. The second semiconductor layer abuts the first section of the first semiconductor layer along an interface, and the doped region is positioned adjacent to the interface.

Abstract: Structures including a vertical heterojunction bipolar transistor and methods of forming a structure including a vertical heterojunction bipolar transistor. The structure comprises a semiconductor substrate including a trench, a first semiconductor layer including a portion adjacent to the trench, a dielectric layer between the first semiconductor layer and the semiconductor substrate, and a second semiconductor layer in the trench. The dielectric layer has an interface with the first semiconductor layer, and the second semiconductor layer includes a portion that is recessed relative to the interface. The structure further comprises a vertical heterojunction bipolar transistor including a collector in the portion of the second semiconductor layer.