Self-organization and Self-repair of a Two-dimensional Nanoarray of Ge Quantum Dots Epitaxially Grown on Si Substrates using Ultrathin SiO2 Films

Abstract

We developed the self-organization technique of two-dimensional nanoarrays of Ge quantum dots (QDs) epitaxially grown on Si substrates using ultrathin SiO2 films, which was featured by the ability to self-repair of the array defects. Nanometer-sized voids (nanovoids) were hexagonally patterned on ultrathin SiO2 films by transcription of the pattern of block copolymer films using selective etching method. The nanovoids worked as nucleation sites for QD growth by Ge deposition onto the patterned ultrathin SiO2 films to form the regularly arranged epitaxial QDs. There were some deficiency sites in the nanovoid arrays created by selective etching. These nanovoid deficiencies, which result in QD nanoarray defects, self-repaired during Ge deposition through the reaction of Ge atoms with the SiO2 films at the nanovoid deficiency sites. The resulting epitaxial QD nanoarrays were elastically strain-relaxed without misfit dislocations and of uniform size owing to the regularly arranged nanovoids with ultrasmall size.