A planar-doped 2D-hole gas base AlGaAs/GaAs heterojunction bipolar transistor grown by molecular beam epitaxy

A novel type of AlGaAs/GaAs heterojunction bipolar transistor (HBT) which uses a two-dimensional (2-D) hole gas base formed by planar doping using molecular-beam epitaxy (MBE) has been demonstrated. The base consists of a submonolayer of Be atoms of sheet concentration 0.5-5*10/sup 13/ cm/sup -2/ which is deposited during growth interruption by MBE. The transistor structure exhibits DC current gains up to 700. The effective base transit time is negligible in these transistors and it is postulated that very high-speed nonequilibrium transport may occur in the collector region.<
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