A new method of two-step growth of InAs/GaAs quantum dots with higher density and more size uniformity

A new two-step growth method for self-assembly growth of InAs quantum dots (QDs) with higher dot density and more size uniformity has been investigated. Using this method, InAs QDs have been grown on GaAs(001) substrates by low pressure metal-organic chemical vapour deposition technology. The samples have been characterized by atomic force microscopy and low temperature photoluminescence measurement. The dot size, dot density and the size uniformity were found to be dependent on the interruption time between the two growth steps and the growth rate of step 2 growth in the two-step growth method. Under similar growth conditions, the dot density and size uniformity of the QDs formed by using this two-step growth method have been improved by 80% and 50%, respectively, when compared to those for QDs grown by the ordinary Stranski-Krastanov growth method.