Vertical ordering and electronic coupling in bilayer nanoscale InAs/GaAs quantum dots separated by a thin spacer layer.

The vertical ordering and electronic coupling in bilayer nanoscale InAs/GaAs quantum dots separated by a thin (7-9 nm) spacer layer has been investigated by transmission electron microscopy and photoluminescence measurements. The nanoscale dots are grown by molecular beam epitaxy (MBE) at 0.028 ML s(-1) growth rate. The active dots having higher monolayer coverages showed reduced ordering due to local strain at the growth surface. Also the active dots with increased monolayer coverage is a probable cause of tunneling-assisted carrier transfer between the dot layers.