LAUSR

Heterojunction bipolar transistors (HBTs) with an In0.49Ga0.51P emitter and a GaAs base and collector were fabricated on epitaxial films grown directly onto Si substrates using a thin germanium (100%) buffer layer. All the materials (Ge, GaAs, In0.49Ga0.51P) were grown epitaxially using metal–organic chemical vapor deposition. The thin germanium buffer layer has a threading dislocation density (TDD) of ~3 × 107 cm−2. The TDD of the active device layers does not worsen and is maintained at ~2 × 107 cm−2, based on the density of dark spots detected in an electron-beam-induced current plan view image. Although the TDD is high, a DC current gain of 95 can be achieved by the In0.49Ga0.51P/GaAs HBT on a Si substrate. In addition, collector current and base current ideality factors (n c and n b ) of 1.07 and 1.23, respectively, and average breakdown voltage (BV cbo ) of 14.2 V can be realized. These results enable applications such as power amplifiers for mobile phone handsets and monolithic integration of HBTs with standard Si CMOS transistors on a common Si platform.