Cathodoluminescence mapping for the determination of n-type doping in single GaAs nanowires

Abstract

We present a new method to determine the doping level of n-type semiconductors at the nanoscale. Low-temperature and room-temperature cathodoluminescence (CL) measurements are carried out on single Si-doped GaAs nanowires. The spectral shift and the broadening of luminescence spectra are a signature of an increased density of electrons. They are compared to CL spectra of well-calibrated planar Si-doped GaAs layers whose doping levels are determined by Hall measurements and compared to previous experimental studies. We infer a n-type doping of $1\times 10^{18}\text{cm}^{-3}$ to $2\times 10^{18}\text{cm}^{-3}$ with a high spatial homogeneity along the nanowire. These results show that cathodoluminescence provides an alternative way to probe carrier concentration in nanostructured and polycrystalline semiconductors, and to map the spatial inhomogeneity of dopants.