Structural and optical properties of columnar (In,Ga)As quantum dots on GaAs (100)

Control of the height of (In,Ga)As quantum dots (QDs) on GaAs (100) substrates is presented. Columnar (In,Ga)As QDs that are homogeneous both in composition and shape along the growth direction are created by molecular beam epitaxy. The columnar QDs are formed on InAs seed QDs by alternating deposition of thin GaAs intermediate layers and monolayers of InAs with extended growth interruptions after each layer. The height of the columnar QDs is controlled by varying the number of GaAs/InAs layers. With increased height the photoluminescence (PL) emission wavelength of the columnar QDs is red-shifted and the line width narrows. Uncapped columnar QDs (surface QDs) emit PL at a long peak wavelength of 1.45 μm at RT due to reduced compressive strain.