Single column compound semiconductor bipolar junction transistor with all-around base

A method of fabricating a structure including single column bipolar junction transistor (BJT) device, comprising:

• obtaining a structure including:
• a semiconductor substrate,
• a dielectric layer on the semiconductor substrate, and
• a vertically extending trench extending through the dielectric layer, the vertically extending trench being configured for aspect ratio trapping;
• forming a vertical column of III-V compound semiconductor material within the vertically extending trench by:
• epitaxially growing a III-V compound semiconductor buffer layer on the substrate,
• epitaxially growing a doped III-V compound semiconductor bottom sublayer having a first conductivity type on the buffer layer,
• epitaxially growing a doped III-V compound semiconductor middle sublayer having a second conductivity type opposite to the first conductivity type on the bottom sublayer;
• and
• epitaxially growing a doped III-V compound semiconductor top sublayer having the first conductivity type on the middle sublayer;
• recessing the dielectric layer to expose at least the top, middle and bottom sublayers of the vertical column;
• forming a plurality of sacrificial layers over the recessed dielectric layer, the plurality of sacrificial layers including a bottom sacrificial layer around the bottom sublayer, a middle sacrificial layer around the middle sublayer and a top sacrificial layer around the top sublayer;
• removing the middle sacrificial layer to form a space between the bottom and top sacrificial layers, and
• epitaxially growing a doped extrinsic base on the middle sublayer and within the space between the bottom and top sacrificial layers, the doped extrinsic base extending entirely around the middle sublayer.