Silicon permeable base transistors fabricated by selective epitaxial growth

A new type of silicon PBT uses lateral selective low-pressure vapour-phase epitaxy to grow ridges with mushroom-like cross-sections leading to self-aligned gate and drain electrodes. Advantages are the lack of any etching damage encountered with etched-groove PBTs and high-temperature process compatibility. First experimental devices with bar widths of 1 mu m exhibited transconductances of 7 mS/mm.