Fabrication of nanoscale structures of InGaN by MOCVD lateral overgrowth

Abstract

Nanoscale InGaN quantum wires and quantum dots (QDs) have been realized on the top of micron size of GaN dots and wires by lateral overgrowth with Si mask using metal-organic chemical vapor deposition (MOCVD). Patterning of the mask was carried out by focused ions beam method to form the stripe and square windows in Si covered MOCVD-GaN substrate. The density, sizes and positions of InGaN nano-structures have been artificially designed and controlled. The characteristics of InGaN nano-structures have been studied by scanning electron microscopy, transmission electron microscopy and cathodoluminescence (CL). A lot of dislocations were found in the interface between underlying and regrown GaN due to damage of ion sputtering. However, the propagation of dislocations was changed the direction parallel to the c plane in the region of laterally overgrown GaN, and no dislocations in the top of GaN dots and wires were observed. Compared to band-gap emission from InGaN/GaN multi-quantum well, the blue-shift of emission peak in InGaN QDs is observed by CL, which suggest that the carriers in InGaN QDs are three-dimensionally confined. It also demonstrates that InGaN structures grown on the top of GaN dots and wires with micron sizes are nanometric scale.