High-performance InP/InGaAs pnp δ-doped heterojunction bipolar transistor J.-H. Tsai, K.-P. Zhu, Y.-C. Chu and S.-Y. Chiu Eur. Phys. J. Appl. Phys., 30 3 (2005) 167-169 Published online: 14 April 2005 DOI: 10.1051/epjap:2005032