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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 × 10 18 cm -3 to 3.3 ×10 18 cm -3 along the axis of a GaAs:Te nanowire grown at 640 °C, and a homogeneous electron concentration of around 6-8 × 10 17 cm -3 along the axis of a GaAs:Te nanowire grown at 620 °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., (© 2022 IOP Publishing Ltd.)

Advanced van der Waals (vdW) heterostructure devices rely on the incorporation of high quality dielectric materials which need to possess a low defect density as well as being atomically smooth and uniform. In this work we explore the use of talc dielectrics as a potentially clean alternative substrate to hexagonal boron nitride (hBN) for few-layer transition metal dichalcogenide (TMDC) transistors and excitonic TMDC monolayers. We find that talc dielectric transistors show small hysteresis which does not depend strongly on sweep rate and show negligible leakage current for our studied dielectric thicknesses. We also show narrow photoluminescence linewidths down to 10 meV for different TMDC monolayers on talc which highlights that talc is a promising material for future van der Waals devices.