EVIDENCE FOR POPULATION-INVERSION IN EXCITED ELECTRON-STATES OF A DOUBLE-BARRIER RESONANT-TUNNELING STRUCTURE

We report evidence for a population inversion between excited electron states of the quantum well of a GaAs-A]GaAs double barrier resonant t unneling structure (DBRTS). The relative populations of the states are determined by photoluminescence spectroscopy of the tunneling electro ns in the structure. When the DBRTS is biased at the fourth electron r esonance, the population of the n = 4 confined level is found to be gr eater than that of the n = 3 state. We show that such a population inv ersion is consistent with a rate equation analysis of the relative pop ulations of the two levels when electrons tunnel into n = 4.