Observation of quantum coherence properties of the hot electron

The authors report the quantum coherence properties of hot electrons for GaInAs/InP systems. They obtained these properties along a path length as long as 280 nm at 77 K, the longest coherent length ever reported. The device used for the observation was a hot-electron transistor. The common-base emitter current-voltage characteristic was observed at 77 K when the collector-base voltage V/sub CB/ is zero. To confirm the quantum interference effect, the authors evaluated this characteristic by the first derivative. Three obvious peaks at 0.04, 0.08, and 0.15 V were observed under 0.2 V, and oscillations with a short period were observed when the applied voltage was over 0.2 V. Forty-eight oscillations were observed between 0.2 and 0.4 V. Three peaks under 0.2 V occurred due to the quantum interference effect in the base region. The period of peaks above 0.2 V was very short in comparison with those below 0.2 V. This threshold voltage, 0.2 V, agrees with the band discontinuity of GaInAs/InP systems. Thus it was judged that the oscillation above 0.2 V occurred due to the quantum interference effect in the InP collector barrier.