An (AlGa)As/GaAs heterojunction bipolar transistor with a resonant-tunnelling collector
An (AlGa)As/GaAs heterojunction bipolar transistor with a double-barrier resonant-tunnelling structure (DBRTS) inserted between the base and the collector has been investigated. Peaks due to resonant-tunnelling electrons have been observed in the device characteristics at 4.2 K. We have extracted the energy levels in the quantum well from the bias voltages for the peaks. The highest measured level corresponds to an energy greater than the barrier height.