Desorption timescales on epitaxial graphene via Fermi level shifting and Reststrahlen monitoring

We report experimental results related to the transience of hole doping in epitaxial graphene-based devices when nitric acid is used as an adsorbent. The desorption processes are monitored under vacuum conditions by electrical and spectroscopic means to extract the relevant timescales from the corresponding data. The measurements are mostly performed at room temperature, with some electrical transport data collected at 1.5 K. The relevant timescales from transport measurements are compared with the results obtained from X-ray photoelecton spectroscopy and Fourier transform infrared spectroscopy measurements, with the latter performed at ambient conditions and accompanied by calculations of the spectra in the Reststrahlen band. This approach can elucidate the reversible nature of hole doping while also providing a suitable alternative for large-scale device doping that need not rely on standard metallic gating.