Figure 12

Plan-view transmission electron microscopy (TEM) images of submonolayer QDs: Thicknesses of the insertions and the compostions are: (a) 5.4 nm, In_0.24Al_0.26Ga_0.48As; (b) 7.8 nm, In_0.19Ga_0.81As; (c) 5.4 nm In_0.24Ga_0.76As. Submonolayer deposition is performed in 0.8 ML InAs cycles (a,c), or in 0.5 ML (b) cycles. The characteristic feature size varies from 15–30 nm (a) to 5–15 nm (b) and 40–60 nm (c). Depending on the AlAs and InAs composition one can adjust the wavelength of SML QDs within 0.75–1.3 μm