In this work we discuss how the occurrence of resonant tunneling through a one-dimensional (1D) double barrier involves some interesting phenomena which have so far been overlooked. The effect of an externally applied electric field is considered, and it is shown that with fully symmetrical barriers it leads to weaker resonances than otherwise possible. Furthermore, the time required for resonance to be fully established is discussed, and it is shown that, depending on the barrier transmission coefficients and experimental conditions, it can be exceedingly long, thus contributing to a reduction of resonance effects on the usual experimental time scale. We also show that resonant tunneling under the usual experimental conditions implies carrier trapping, hence a buildup of space charge available for modifying the potential-energy barrier. Different current behaviors then result from the inherent feedback mechanism. The effects of temperature on the measured current are finally discussed. © 1984 The American Physical Society.