1 research outputs found
Determination of n‑Type Doping Level in Single GaAs Nanowires by Cathodoluminescence
We
present an effective method of determining the doping level
in n-type III–V semiconductors at the nanoscale. Low-temperature
and room-temperature cathodoluminescence (CL) measurements are carried
out on single Si-doped GaAs nanowires. The spectral shift to higher
energy (Burstein–Moss shift) and the broadening of luminescence
spectra are signatures of increased electron densities. They are compared
to the CL spectra of calibrated Si-doped GaAs layers, whose doping
levels are determined by Hall measurements. We apply the generalized
Planck’s law to fit the whole spectra, taking into account
the electron occupation in the conduction band, the bandgap narrowing,
and band tails. The electron Fermi levels are used to determine the
free electron concentrations, and we infer nanowire doping of 6 ×
10<sup>17</sup> to 1 × 10<sup>18</sup> cm<sup>–3</sup>. These results show that cathodoluminescence provides a robust way
to probe carrier concentrations in semiconductors with the possibility
of mapping spatial inhomogeneities at the nanoscale