Temperature studies of InAlAs-InGaAs-InAlAs double heterojunction bipolar transistors with no current blocking

In this paper, elimination of current blocking for the temperature range 77 K to 400 K is experimentally demonstrated for all ternary InAlAs-InGaAs-InAlAs double heterojunction bipolar transistors of emitter area 100 × 100 νm2. The wafers were grown by molecular beam epitaxy without using any complex growth techniques such as coherent heterointerfaces for reflection and penetration superlattice or quaternary alloys for grading. A room temperature breakdown (BVceo) of 5 V is achieved despite the collector thickness of less than 2000 and heavy dipole doping of 4 × 1018 cm -3. Activation energies calculated from the Gummel plots indicate the shift of the transport mechanism across the junction from thermionic emission to predominantly tunneling as the temperature is lowered to 77 K. © 2010 IOP Publishing Ltd.