Physics of base charge dynamics in the three port transistor laser

The base charge dynamics of the quantum-well (QW) transistor laser (TL) is analyzed by constructing a model based on earlier incomplete charge control analysis. We extend Kirchhoff's Law to include electrical and consistently "optical" elements. The model yields, via microwave measurements (and resolvable picosecond responses), physical quantities associated with TL base-charging, permitting the extraction of a base QW charge density, nQW =2× 1016 cm-3, consistent with calculation by current continuity. The low density implies quasi-Fermi level discontinuity in the TL base, and indicates that the base QW charge level is not as important as the current driving the QW and supplying electron-hole recombination.