Novel P-Type Al(In)GaN Superlattice Structures for High-Performance Bipolar Transistors.

Period of Performance: 08/19/2003 - 02/15/2004


Phase 1 SBIR

Recipient Firm

SVT Assoc., Inc.
7620 Executive Drive
Eden Prairie, MN 55344
Principal Investigator


For ultra-high power, high temperature electronics, III-N wide-bandgap materials offer substantial advantages over other semiconductor material systems. Remarkable power densities have been achieved in AlGaN-based high electron mobility transistors (HEMTs) for operation at high frequencies. Even higher power densities, with lower noise and better linearity, have been projected for AlGaN/GaN heterojunction bipolar transistors (HBTs). The main issues preventing the realization of such high-performance HBTs are 1) the problem with the p-type doing of the base region and 2) the emitter to collector current leakage. We are proposing a new HBT design with a novel structure in the base layer, to solve the first problem, in conjunction with growth on substrates with low density of treading dislocations to address the second issue. We will design and fabricate these HBTs by molecular beam epitaxy (MBE) for high-frequency operation at high temperatures and very high power densities (>10 W/mm). SVT Associates has already demonstrated high temperature (425 oC) operation of nitride---based heterojunction bipolar transistors (HBTs). The proposed new HBT design would eliminate some of the main problems in the high-power and high-frequency operation of these devices. These HBTs will offer high transistor linearity and low phase noise, inherent in bipolar designs, that are required for economically significant digital transmission applications. The chemically and thermally stable, high-power transistors would have numerous commercial applications in aerospace, automotive, geothermal/oil drilling, portable computation and digital communications industries.