Effects of interdiffusion on the luminescence of InGaAs/GaAs quantum dots

Abstract

Large energy shifts in the luminescence emission from strained InGaAs quantum dots are observed as a result of postgrowth annealing and also when raising the upper cladding layer growth temperatures. These blueshifts occur concurrently with narrowing (from 61 to 24 meV) of the full width at half-maxima for the emission from the quantum dot ensemble. These energy shifts can be explained by interdiffusion or intermixing of the interfaces rather than strain effects due to variations in capping layer thickness. Temperature behavior of the luminescence in annealed and nonannealed samples indicates a change in the shape and depth of the quantum dot confining potential. Quenching of the wetting layer luminescence after interdiffusion is also observed.

Effects of rapid thermal annealing on device characteristics of InGaAs∕GaAs quantum dot infrared photodetectors

“…This has been observed previously in many studies, as a result of significant thermal interdiffusion. 9,10,13,19 However, for our 15-layer QDIP structure, the interdiffusion was initiated at a lower temperature of 700°C ͓compared with 750°C for single and 3-layer QDs ͑Ref. 10͔͒, due to a larger accumulated strain.…”

Annealing effects on the microstructure of Ge/Si(001) quantum dots

“…2,3,5 We believe that the averaging of the Ge concentration among islands in different layers is one of the main reasons contributing to the narrowing of the PL peaks.…”

“…1 Photoluminescence ͑PL͒ investigations suggest blueshift in the interband energy and narrowing of the PL linewidth after thermal annealing. [2][3][4] Although the reasons for this shift have been investigated from a microstructural point of view, 5,6 little attention has been paid to the effects of thermal annealing on compositional change within QDs. This letter reports an energy-filtering transmission electron microscopy ͑TEM͒ study of the effects of annealing on QD stacks.…”

Electron microscopic and optical investigations of the indium distribution in GaAs capped InxGa1−xAs islands

“…[1][2][3] The exact determination of the indium concentration in the grown structure, however, is a problem, particularly after the final overgrowth of the islands with the GaAs cap layer. 4 In this letter we present a structural analysis of buried In x Ga 1Ϫx As islands by cross-sectional high-resolution transmission electron microscopy ͑HRTEM͒ after overgrowth with a GaAs cap layer. Both the dimension and shape as well as the indium concentration profile have been determined.…”