AlGaAs/GaAs Npn heterojunction bipolar transistors have been grown by molecular beam epitaxy on Si (311) substrates utilizing a GaAs buffer layer as thin as 2 mu m and fabricated using a self-aligned base contact process. Reflection high-energy electron diffraction patterns correspond with antiphase domain-free growth. Direct current measurements for a 70 x 70 mu m(2) device reveal a small-signal common-emitter current gain of 10 and collector-emitter breakdown of 13 V at a collector current of 1.8 kA/cm(2). These results indicate that further optimization in growth technique may render the growth of GaAs-on-Si (311) a viable candidate for application in high-power integration.