Understanding the Parameters Affecting the Photoluminescence of Silicon Nanoparticles

MANUEL J. LLANSOLA PORTOLES; REINALDO PIS DIEZ; MARÍA L. DELLARCIPRETE; PAULA CAREGNATO; JUAN JOSE ROMERO; DANIEL O. MÁRTIRE; OMAR AZZARONI; MARCELO CEOLÍN; MONICA C. GONZALEZ

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 116 p. 11315 - 11325

1932-7447

Silicon nanoparticles of 1−5 nm size (SiNPs) were synthesizedby a bottom-up (BU) approach involving a chemical wet method. Thecontribution of different emitters to the overall excitation−emission matrix wasanalyzed on the assumption that pure substances existing in a unique formshow an excitation wavelength-invariant emission spectrum. The occurrence ofemitters differing in size and aggregation was supported by transmissionelectron microscopy (TEM), small-angle X-ray scattering (SAXS), timeresolvedsingle photon counting, and time-resolved anisotropy experiments.The effect on photoluminescence (PL) of the particle surface oxidation as aresult of aging is studied and compared to that of surface oxidized particlesobtained by a top-down (TD) approach following an electrochemical methodwith HF etching. Surface oxidation to SiOx seems to introduce two differenteffects on the SiNP PL. An emission originated in surface states associated toSiOx was identified and observed for SiNPs synthesized by both BU and TD approaches. Blue-shifted excitation−emissionspectra associated to a silicon core in embedded SiOx nanostructures were also identified. Theoretical studies were carried out tohelp understand the observed results.