Imaging the electric properties of InAs/InP(001) quantum dots capped with a thin InP layer by conductive atomic force microscopy: Evidence of memory effect

摘要

Conductive atomic force microscopy has been used to study the topography and the electric properties of InAs quantum dots (QDs) grown by metal organic vapor phase epitaxy on a n-type InP(001) substrate and covered with a 5 nm thick InP cap layer. Images reveal that the cap layer has not entirely covered the surface, but has formed rounded terracelike structures surrounding the QDs. A high current is detected on the QDs, about ten times less on the terraces, and not detectable on the wetting layer. Charges can be trapped inside the QDs and the surrounding terraces in forward bias conditions with a temporary memory effect and discharged in reverse bias.