Improved luminescence intensity and stability of nanocrystalline silicon due to the passivation of nonluminescent states

Luminescence intensity and stability of nanocrystalline silicon (nc-Si) passivated with oxygen and hydrogen atoms have been studied by using electron-spin resonance and photoluminescence measurements. The oxygen-passivated nc-Si with low-density P-ce' centers (luminescent states) and high-density P-b centers (nonluminescent states) exhibited weak red luminescence. When the nc-Si surface was passivated with hydrogen atoms in addition to oxygen atoms using a hydrofluoric acid solution treatment, the intensity of red luminescence increased more than one order of magnitude with an increase of P-ce' centers and reduction of P-b centers on the surface. Furthermore, the red luminescence of nc-Si was very stable even after aging beyond one year, owing to the existence of only P-ce' centers and the absence of P-b centers. These results are a strong indication that the improved luminescence intensity and stability is due to the hydrogen and oxygen passivation of nonluminescent states. (c) 2005 American Institute of Physics.