HIGH-GAIN EXCITONIC LASING FROM A SINGLE INAS MONOLAYER IN BULK GAAS

We report the observation of highly efficient laser emission from a si ngle InAs layer with an effective thickness of 1.5 monolayers (hilt) e mbedded in bulklike GaAs. Lasing action is obtained at the wavelength of the InAs thin-layer luminescence (870 nm) by cw optical pumping wit h a threshold power density of 0.9(3) kW/cm(2) at 10 K. Gain measureme nts yield a very high material gain of 1.0(5) x 10(4) cm(-1) for the I nAs layer when pumped with similar to 10 kW/cm(2) at low temperatures. The 0 dimensional character of the emission as determined from cathod oluminescence and the absence of band-gap renormalization with increas ing pump level speak for an excitonic mechanism of population inversio n. (C) 1998 American Institute of Physics.