STM/STS study of superconducting diamond

We present a scanning tunneling microscopy/spectroscopy (STM/STS) study of synthetic polycrystalline boron-doped diamond in the temperature range 0.5-4.3 K. At 4.3 K the sample-surface was very non-uniform and tunneling I(V) spectra were typical for p-type semiconductors. After cooling below the superconducting transition temperature, we detected and measured the superconducting gap of diamonds. At temperatures around 0.5 K the energy gap was around 0.8 and 1 mV (for two different samples).