Stimulated emission from monolayer thick quantum-well heterostructures

Summary form only given. Stimulated emission from clearly defined quantum-well transitions has been observed from single quantum wells as thin as one monolayer. These results are unexpected, since previous experimental and theoretical work has indicated that if the well width is comparable to or smaller than the scattering path length of the electrons or holes, carrier collection becomes inefficient and the quantum well cannot support stimulated emission. Well-defined confined particle transitions were observed from the GaAs quantum wells for thicknesses as thin as two monolayers (5.65 AA) and from pseudomorphic InAs quantum wells for thicknesses as thin as one monolayer (3 AA). Continuous-wave laser thresholds as low as 820 W/cm², J_eq=340 A/cm² from the pseudomorphic samples and 1740 W/cm², 720 A/cm² from the lattice-matched samples have been measured at 77 K. Data are presented which demonstrate that monolayer thick quantum wells can operate efficiently as lasers at low thresholds despite previous experimental and theoretical predictions to the contrary.