Synthesis, structure, and optical properties of colloidal GaN quantum dots

Colloidal chemistry was used to synthesize GaN quantum dots. A GaN precurso r, polymeric gallium imide, {Ga(NH)(3/2)}(n), which was prepared by the rea ction of dimeric amidogallium with ammonia at room temperature, was heated in trioctylamine at 360 degrees C for one day to produce GaN nanocrystals. The GaN particles were separated, purified, and partially dispersed in a no npolar solvent to yield transparent colloidal solutions that consisted of i ndividual GaN particles. The GaN nanocrystals have a spherical shape and me an diameter of about 30 +/- 12 Angstrom. The spectroscopic behavior of coll oidal transparent dispersion has been investigated and shows that the band gap of the GaN nanocrystals shifts to slightly higher energy due to quantum confinement. The photoluminescence spectrum at 10 K (excited at 310 nm) sh ows band edge emission with several emission peaks in the range between 3.2 and 3.8 eV, while the photoluminescence excitation spectrum shows two exci ted-state transitions at higher energies. (C) 1999 American Institute of Ph ysics. [S0003-6951(99)04230-8].