LASING PROPERTIES OF A SINGLE, HIGHLY STRAINED INAS MONOLAYER IN BULKGAAS

We have studied the stimulated emission characteristics of a single 1. 5-monolayers-thick InAs layer in bulklike GaAs. Lasing action is obtai ned at the wavelength of the InAs thin-layer excitonic luminescence (8 70 nm) by cw-optical pumping with a threshold power density of 0.9(3)k W/cm(2) at 10 K. Gain measurements yield a very high material gain of 1.0(5)x10(4)cm(-1) for the InAs layer when pumped with 12 kW/cm(2) at low temperatures. This value is twice as high as that obtained for rel ated InGaAs/InGaAsP multiple quantum wells using much larger pump powe r densities, but comparable to the gains measured recently in InAs/GaA s quantum dot lasers. The large material gain and the absence of bandg ap renormalization effects with increasing pump level speak for an exc itonic mechanism of population inversion characteristic of low-dimensi onal lasing nanostructures.