Control over the parameters of InAs-GaAs quantum dot arrays in the Stranski-Krastanow growth mode

The effect of the growth temperature on the density, lateral size, and height of InAs-GaAs quantum dots (QD) has been studied by transmission electron microscopy. With the growth temperature increasing from 450 to 520°C, the density and height of QDs decrease, whereas their lateral size increases; i.e., the QDs are flattened. The blue shift of the photoluminescence line indicates decreasing QD volume. The observed behavior is in agreement with the thermodynamic model of QD formation. The effect of lowering the substrate temperature immediately after the formation of QDs on the QD parameters has been studied. On lowering the temperature, the lateral size of QDs decreases and their density increases; i.e., the parameters of QD arrays tend to acquire the equilibrium parameters corresponding at the temperature to which the cooling is done. The QD height rapidly increases with cooling and may exceed the equilibrium value for a finite time of cooling, which enables fabrication of QD arrays with a prescribed ratio between height and lateral size by choosing the time of cooling.