ABSTRACTSuperlattices and quantum wells of Znl-xCdxSe/ZnSe,
and heterostructures based on ZnSe/CdSe digital alloys have been grown by
molecular beam epitaxy (MBE). Their optical properties were studied with
particular emphasis on excitonic absorption and photopumped stimulated
emission. Excitonic absorption is easily observable up to 400 K, and is
characterized by extremely large absorption coefficients (α =
2×105cm−1). Optically pumped lasing action is
obtained at room temperature with a typical threshold intensity of 100
kW/cm2. The lasing mechanism in these II-VI quantum wells
appears to be quite different from that in the better studied III-V
materials: in our case, the onset of stimulated emission occurs
before the saturation of the excitonic absorption, and
the stimulated emission occurs at an energy lower than that
of the excitonic absorption.
