Negative differential conductance due to resonant states in GaInAs/InP hot-electron transistors

We have observed dips with negative values in the curve of the differential conductance of the base versus the base-emitter voltage dIB/dVBE at 77 K in GaInAs/InP hot-electron transistors grown by organometallic vapor phase epitaxy. The efficiency of the hot-electron transmission across the 40-nm-thick base was more than 0.99. In comparison with a theoretical model considering that observed dips should have been caused by the resonant states in the base well, the phase relaxation time of the hot electron is estimated to be in the order of 0.1 ps or longer.