High-gain excitonic lasing from a single InAs monolayer in bulk GaAs

Abstract

We report the observation of highly efficient laser emission from a single InAs layer with an effective thickness of 1.5 monolayers (ML) embedded in bulklike GaAs. Lasing action is obtained at the wavelength of the InAs thin-layer luminescence (870 nm) by cw optical pumping with a threshold power density of $\text{0.9(3)\hspace{0.17em}}{\mathrm{kW/cm}}^{\mathrm{2}}$ at 10 K. Gain measurements yield a very high material gain of ${\text{1.0(5)×10}}^4\hspace{0.17em}{\mathrm{cm}}^{\mathrm{-1}}$ for the InAs layer when pumped with $\text{∼10\hspace{0.17em}}{\mathrm{kW/cm}}^{\mathrm{2}}$ at low temperatures. The 0 dimensional character of the emission as determined from cathodoluminescence and the absence of band-gap renormalization with increasing pump level speak for an excitonic mechanism of population inversion.