Cathodoluminescence mapping of electron concentration in MBE-grown GaAs:Te nanowires

Cathodoluminescence mapping is used as a contactless method to probe the electron concentration gradient of Te-doped GaAs nanowires. The room temperature and low temperature (10 K) cathodoluminescence analysis method previously developed for GaAs:Si is first validated on five GaAs:Te thin film samples, before extending it to the two GaAs:Te NW samples. We evidence an electron concentration gradient ranging from below 1 x 10(18) cm(-3) to 3.3 x10(18) cm(-3) along the axis of a GaAs:Te nanowire grown at 640 degrees C, and a homogeneous electron concentration of around 6-8 x 10(17) cm(-3) along the axis of a GaAs:Te nanowire grown at 620 degrees C. The differences in the electron concentration levels and gradients between the two nanowires is attributed to different Te incorporation efficiencies by vapor-solid and vapor-liquid-solid processes.