Quantum confinement effect of amorphous GaN quantum dots prepared by pulsed-laser ablation

Amorphous GaN quantum dots (a-GaN QDs) smaller than the Bohr radius (I I nm) were successfully fabricated at room temperature by a laser ablation using a highly densified GaN target. The mean particle size of the a-GaN QDs was 7.9 nm for the films deposited at the Ar pressure of 50 Pa, 5.2 nm at 100 Pa and 4.4 nm at 200 Pa. In particular, the room temperature photoluminescence (PL) and absorption spectra revealed that the a-GaN QDs fabricated under the Ar pressures of 100 and 200 Pa exhibited a strong emission band centered at 3.9 eV, which is about 0.5 eV blue-shifted from the band gap energy of the bulk GaN crystal, confirming the quantum confinement effect.