npn AlGaN/GaN heterojunction bipolar transistors and GaN bipolar junction transistors with regrown C-doped GaAs in the base regions

• Published in: Solid-state electronics 2000-12, Vol.44 (12), p.2097-2100
• Main Authors: Dang, G, Luo, B, Zhang, A.P, Cao, X.A, Ren, F, Pearton, S.J, Cho, H, Hobson, W.S, Lopata, J, van Hove, J.M, Klaassen, J.J, Polley, C.J, Wowchack, A.M, Chow, P.P, King, D.J
• Format: Article
• Language: English
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/S0038-1101(00)00112-X

Low resistance ohmic contacts are difficult to form on p-type GaN and AlGaN due to the relatively high ionization energy of Mg in GaN and AlGaN. A carbon-doped GaAs grown on p-GaN prior to ohmic metallization has been shown to improve contact resistance to p-GaN. npn AlGaN/GaN heterojunction bipolar transistors and GaN bipolar junction transistors have been demonstrated by employing a regrowth C-doped GaAs to the p-GaN base regions. GaN/AlGaN epilayers were grown with a molecular beam epitaxy system and C-doped GaAs (10 20 cm −3) was regrown on the devices (∼500 Å) by metal organic chemical vapor deposition using SiO 2 as mask. Very high current densities were achieved for common base operation in both device types and devices were operable at 250°C.