Designer Ge quantum dots on Si: A heterostructure configuration with enhanced optoelectronic performance

Abstract

An otherwise random, self-assembly of Ge quantum dots (QDs) on Si has been controlled by nano-patterning and oxidation to produce QDs with desired sizes, locations, and depths of penetration into the Si substrate. A heterostructure consisting of a thin amorphous interfacial oxide between the Ge QD and the Si substrate is shown to improve crystalline quality by de-coupling the lattice-matching constraint. A low dark current density of 1.1 μA/cm2 and a high photocurrent enhancement up to 35 000 and 1500, respectively, for 1.5 mW incident illumination at 850 nm and 1160 nm was measured on our Ge QD-based metal-oxide-semiconductor photodiodes.