BACKGROUND

Technical Field

The present disclosure relates to a bipolar junction transistor (BJT) structure, and more particularly to lateral bipolar junction transistors.

Description of the Related Art

Heterojunction bipolar junction transistors (HBTs) known in the art include a heterojunction, i.e., a junction of two semiconductor materials having different band gaps, that coincide with a p-n junction between the base and the emitter. The heterojunction at which two different semiconductor materials having different band gaps are joined coincide with the p-n junction. The wider band gap of the emitter relative to the band gap of the base in an HBT increases the current gain relative to a bipolar junction transistor employing a same semiconductor material across the base and the emitter and having similar physical dimensions and doping profiles for the base and emitter.

SUMMARY

In one aspect, the present disclosure provides a lateral bipolar junction transistors (LBJT) device. The bipolar junction transistor may include a base region of a first III-V semiconductor material having the first band gap; and emitter and collector regions present on opposing sides of the base region. The emitter and collector regions are composed of a second III-V semiconductor material having a wider band gap than the first III-V semiconductor material. A dielectric region is present underlying the base region, emitter region and the collect region. The dielectric region has an inverted apex geometry. The sidewalls of the dielectric region extending to the apex of the inverted apex geometry are present on facets of a supporting substrate III-V semiconductor material having a {110} crystalline orientation.

In another embodiment, the bipolar junction transistor includes a substrate of a III-V semiconductor material having a trench with an inverted apex geometry. The sidewalls of the trench that lead to the inverted apex are provided by facets of the supporting substrate III-V semiconductor material having a {110} crystalline orientation. A dielectric fill is present within the trench having the inverted apex geometry. The dielectric fill having a planar surface opposite a base of the dielectric fill that is in contact with the inverted apex of the trench. The base region of the bipolar junction transistor is present between an emitter region and a base region of the bipolar junction transistor. The emitter region, base region and the collector region of the bipolar junction transistor are present on the planar surface of the dielectric fill.

In another aspect, a method of forming a bipolar junction transistor is provided that includes forming a III-V semiconductor material for a base region atop a III-V semiconductor substrate; and forming emitter and collector regions on opposing sides of the base region. In a following step, the III-V semiconductor substrate is etched selectively to facets having a {110} crystalline orientation. The etch process provides a trench having the inverted apex geometry underlying at least the base region.

These and other features and advantages will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

