Optical characterizations of doped silicon nanocrystals grown by co-implantation of Si and dopants in SiO₂

Journal Article · Tue Oct 14 04:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4898038· OSTI ID:22305783

Frégnaux, M.; Khelifi, R.; Muller, D.

Co-implantation, with overlapping implantation projected ranges, of Si and doping species (P, As, and B) followed by a thermal annealing step is a viable route to form doped Si nanocrystals (NCs) embedded in silica (SiO₂). In this paper, we investigate optical characterizations of both doped and un-doped Si-NCs prepared by this method. The effective NC presence in the oxide layer and their crystallinity is verified by Raman spectrometry. Photoluminescence (PL) and PL excitation measurements reveal quantum confinement effects and a gradual PL quenching with increasing dopant concentrations. In un-doped NC, the measured Stokes shift remains constant and its value ~0.2 eV is almost twice the Si–O vibration energy. This suggests that a possible radiative recombination path is a fundamental transition assisted by a local phonon. PL lifetime investigations show that PL time-decays follow a stretched exponential. Using a statistical model for luminescence quenching, a typical NC diameter close to 2 nm is obtained for As- and P-doped samples, consistent with our previous atomic probe tomography (APT) analyses. APT also demonstrated that n-type dopant (P and As) are efficiently introduced in the NC core, whereas p-type dopant (B) are located at the NC/SiO₂ interface. This last observation could explain the failure of the luminescence-quenching model to determine NC size in B-doped samples. All together, these experimental observations question on possible different carrier recombination paths in P or As doped NC compared to B one's.

• OSTI ID: 22305783
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 14 Vol. 116; ISSN JAPIAU; ISSN 0021-8979
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
ARSENIC ADDITIONS
BORON ADDITIONS
CARRIERS
DOPED MATERIALS
EXCITATION
INTERFACES
LAYERS
LIFETIME
NANOMATERIALS
NANOSTRUCTURES
PHOSPHORUS ADDITIONS
PHOTOLUMINESCENCE
RAMAN SPECTROSCOPY
RECOMBINATION
SILICON
SILICON OXIDES
TOMOGRAPHY