AlGaN/GaN heterojunction bipolar transistors grown by metal organic chemical vapour deposition

Heterojunction bipolar transistors based on aluminium gallium nitride/galli um nitride (AlGaN/GaN) structures have been fabricated and characterised. T he devices were grown by metal organic chemical vapour deposition on e-plan e sapphire substrates. The Npn structure consists of an n-GaN layer followe d by an n(+)-GaN subcollector contact, an unintentionally doped GaN collect or, p-GaN base, and an N-Al(0.1)G(0.9)N emitter with n(+)-GaN contact. Devi ces yielded good transistor performance with a DC current gain as high as 1 00 at room temperature.