SUMMARYAs a promising resonant tunneling structure for reduction of tunneling time, the "asymmetric rectangular double-barrier structure with an acceleration well" is proposed. Analytical expressions are derived for the tunneling transmission coefficient of the electrons and for the resonant condition. Also, the condition for the shortest tunneling time is analytically studied by using the dwell time as the tunneling time. From the resonant condition, the width of each layer can be determined for a given resonant energy. The resultant dwell time is calculated and discussed in terms of both theoretical and numerical analysis. Although the model proposed in this research is an idealized one, the proposed structure and the obtained results are considered useful in the design of tunneling devices in the sense that the tunneling time can be controlled.
SUMMARYThe dwell time is analyzed in asymmetric doublebarrier structures in which perfect resonance can occur when a bias voltage is applied. By taking into account the effective mass of the electron in each region, theoretical analytical expressions are derived for the tunneling transmission coefficient and the total resonance condition in the presence of a bias voltage. The bias voltage at which perfect resonance occurs is called the "resonance voltage." The dependence of the probability density and dwell time of electrons on the resonance voltage is analyzed numerically. When the resonance voltage is increased while the resonant energy is kept constant, the dwell time is found to decrease. It is concluded that this occurs because the acceleration of the electrons is larger for a higher bias voltage, so that the probability density in the well region is smaller and the dwell time becomes shorter.
GaSb single crystals with different Er concentrations have been studied by cathodoluminescence in the scanning electron microscope. Low Er doping has been found to reduce the concentration of native acceptors. In crystals with higher Er concentrations, Er-Sb precipitates form and doping becomes less efficient in suppressing the acceptors. In these samples intraionic Er luminescence is observed.
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