Bandgap engineering of self-assembled InAs quantum dots with a thin AlAs barrier

Narrowing of ground energy level distribution in an array of InAs/AlAs QDs by post grown annealing

“…Observed changes in PL of the InAs/AlAs QDs are similar to early observed for InAs/GaAs ones [1][2][3][4]. It was explained by interdiffusion, which results in two effects: (i) effective increase in the dots size, which would reduce the effect of the size distribution leading to a narrower PL band; and (ii) change in the dots composition resulting in shallower confining potential and a blue shift in the emission [1].…”

“…Such difference between interdiffusion in pure InAs and InGaAs alloy QDs embedded in GaAs matrix is confirmed by literature data. PL of pure InAs/GaAs QDs demonstrates appreciable blue shift at the annealing temperatures of about 600-650 ºC [3,4], while PL In 0.6 Ga 0.4 As/GaAs QDs does not shift at all at the annealing temperature of 700 ºC [8]. We suppose that similar behaviour takes place for system of the InAs/AlAs QDs.…”

“…Indeed, InAs/AlAs QDs grown by Jung et. al [4] at temperature of 440 ºC that is in seventy degrees lower than in this study and therefore contained a smaller fraction of AlAs in QDs demonstrate blue shift of they PL band at the annealing temperatures as low as 550 ºC.…”

“…In order to decrease this dispersion growth and post growth treatment techniques were proposed. Recently, it was shown that a short-time high temperature annealing could be successfully used to decrease the width of the photoluminescence (PL) line in an array of InAs/GaAs QDs [1][2][3][4]. In this work we study effect of a high temperature annealing on photoluminescence and structure of InAs QDs embeded in an AlAs matrix.…”

X-ray mapping in a scanning transmission electron microscope of InGaAs quantum dots with embedded fractional monolayers of aluminium

“…The motivation for this work is based on earlier results by other groups who showed that the optical emission of epitaxial InGaAs quantum dots (QDs) sandwiched between GaAs barriers can be tuned by replacing the GaAs below the QDs by either AlAs [14] or (InAlGa)As [15], or the GaAs cap on top by AlAs [16], or both lower and upper barriers by AlAs [17]. Here, we tried to incorporate ultra-thin AlAs layers directly within the InAs QDs.…”