Dislocation-induced electron and hole levels in InAs quantum-dot Schottky diodes

Abstract

Self-assembled InAs quantum dots (QDs) have been incorporated into GaAs Schottky diodes. We intentionally introduce defects by growing the QDs above the critical thickness for plastic relaxation. The strain-relaxed QDs introduce electrically active defects in n- as well as p-type diodes. We identify dislocation induced defects and point defects, and can show that in n-type GaAs the EL6 defect plays a major role in the relaxation of QDs. Furthermore, we compare the introduction of defects in strain relaxed QDs grown by looped and non-looped deposition and depending on an in-situ annealing step. We observe that looped deposited QDs exhibit a better quality compared to non-looped QDs even if they are grown beyond the critical thickness for plastic relaxation. An introduction of an annealing step after the growth of the QDs completely removes the defects in both QD system.