Determination of n-Type Doping Level in Single GaAs Nanowires by Cathodoluminescence

Abstract

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 to 1 × 10 cm. 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.

Investigation of GaN nanowires containing AlN/GaN multiple quantum discs by EBIC and CL techniques

“…To get an insight on the spatial distribution of these high energy emission peaks in single NWs, CL analyses were performed on individual NWs at 15 K. In CL measurements, the photons emitted due to radiative recombination events can be associated to the excitation electron beam position hence building a hyper-spectral map where a spectrum is associated to each pixel. By integrating the luminescence intensity associated to each pixel in different wavelength ranges, it is possible to obtain spectrally filtered maps of individual NWs [36][37][38]. The measurements were performed with an Attolight "Chronos" cathodoluminescence microscope with an acceleration voltage of 2 kV and the spectra were recorded on an Andor Newton CCD camera with a Horiba dispersive spectrometer using a 150 grooves/mm grating.…”

Threshold reduction and yield improvement of semiconductor nanowire lasers via processing-related end-facet optimization

“…This blue shi is associated to the change in material refractive index induced by the increased photo-excited carrier density, as previously reported for GaAs. 6,8,[21][22][23] At high excitation uence, we observe a lasing peak line-width of $10 nm, which is larger than that seen just above threshold (and larger than typically observed for nanowire lasers). We attribute this large line-width to a smearing effect caused by the carrier density (and hence effective refractive index) varying during the laser emission.…”

Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy

“…SEM-CL is more commonly used for this aim. There are several studies in the literature using this technique to measure the optical properties [ 168 ], for different purposes such as examining the effect of chemical modifications such as nitridation [ 169 ], determining the doping level [ 170 ], observing the effect of stacking sequence within the structure [ 171 ], and polarity [67]. It can also be used to study the carrier concentration [ 172 ].…”