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

Heterojunction bipolar transistors based on aluminum gallium nitride/gallium nitride (AlGaN/GaN) structures have been fabricated and characterized. The devices were grown by metal organic chemical vapour deposition on c-plane sapphire substrates. The Npn structure consists of an n-GaN layer followed by an n⁺-GaN subcollector contact, an unintentionally doped GaN collector, p-GaN base, and an N-Al_0.1G_0.9N emitter with n⁺-GaN contact. Devices yielded good transistor performance with a DC current gain as high as 100 at room temperature.