Strain-induced direct band gap LaAlO3 nanocrystals

Abstract

Bulk LaAlO3 has a rhombohedral structure at ambient conditions. However, when the diameter of free-standing LaAlO3 nanocrystal is smaller than 100 nm, it has at room temperature a thermodynamically stable cubic structure with indirect band gap. The LaAlO3 nanocrystals embedded in amorphous Lu2O3 matrix were fabricated using pulsed laser deposition method and rapid thermal annealing technique. The LaAlO3 nanocrystals experience a net deviatoric strain from Lu2O3 matrix, which causes a distortion of the AlO6 octahedra. This leads to the growth of strain-induced direct band gap LaAlO3 nanocrystals with rhombohedral structure. Strain engineering is an effective tool for tailoring the properties of LaAlO3 nanocrystals.