Monolithic integration of InP-based transistors on Si substrates using MBE

We report on a direct epitaxial growth approach for the heterogeneous integration of high-speed III–V devices with Si CMOS logic on a common Si substrate. InP-based heterojunction bipolar transistor (HBT) structures were successfully grown on Si-on-lattice-engineered- substrate (SOLES) and Ge-on-insulator-on-Si (GeOI/Si) substrates using molecular beam epitaxy. Structurally, the epiwafers exhibit sharp interfaces and a threading dislocation density of 3.5×107cm−2 as measured by plan-view transmission electron microscopy. HBT devices fabricated on GeOI/Si substrates have current gain of 55–60 at a base sheet resistance of 650–700Ω/sq, and ft and fmax of around 220GHz. HBT structures with DC and RF performance similar to those grown on lattice-matched InP were also achieved on patterned SOLES substrates with growth windows as small as 15×15μm2. These results demonstrate a promising path of heterogeneous integration and selective placement of III–V devices at arbitrary locations on Si CMOS wafers.