Stimulated emission in ultrathin (20 Å) AlxGa1−xAs-GaAs single quantum well heterostructures

Abstract

Spontaneous and stimulated emission spectra from a series of Al_xGa_1−xAs‐GaAs single quantum well heterostructures are demonstrated for well widths as thin as 20 Å. These undoped samples, grown by molecular beam epitaxy, are the thinnest single quantum wells ever reported to support stimulated emission. Laser thresholds are generally quite low (1.2 kW/cm²) despite the fact that the single well is undoped and of dimensions which were previously thought to be too small to effectively collect excess carriers (L_z≪scattering path length). A simple model based on the spatial extent of the wave function, rather than the well width, is proposed to explain the experimental results.