Function Of Capping Layer Thickness Research Articles

Strain effects on individual quantum dots: Dependence of cap layer thickness

We have studied the effects of strain on individual self-assembled quantum dots (QDs) exemplified by InP dots embedded in GaInP. The quantum dot sample was etched from the top and in this way the amount of capping material was reduced. In a sequence of etch cycles, the cap layer was thinned, and the photoluminescence from several individual QDs could be followed as a function of cap layer thickness. The evolution of the emission spectra clearly depended on the quantum dot size. We interpret this as arising from differences in the aspect ratio for quantum dots of different sizes. The influence of the capping layer, for different QD geometries, was modeled using deformation potential theory with the strain calculated using a full three-dimensional linear elasticity model. The results agree well with the experimental observations. (Less)

Observation of strain effects in semiconductor dots depending on cap layer thickness

We have investigated the photoluminescence emission energy of InP dots as a function of cap layer thickness. We find a strong blue-shift with increasing cap layer thickness. The strain tensor in the dot as well as in the surrounding matrix has been modeled using finite element methods and the band gap has been calculated using deformation potential theory. We find good agreement between calculation and experiment. For uncapped dots we find that the emission energy is lower than for biaxially strained InP, and is indeed close to unstrained InP.

Strain Effects in InP Dots in between Barriers of GaInP

AbstractWe have investigated the photoluminescence emission energy of InP dots as a function of cap layer thickness. We find a strong blue-shift with increasing cap layer thickness. The strain tensor in the dot as well as in the surrounding matrix has been modelled using finite element methods and the band-gap has been calculated using deformation potential theory. We find good agreement between calculation and experiment. For uncapped dots we find that the emission energy is lower than for biaxially strained InP, and is indeed close to unstrained InP.