Published online by Cambridge University Press: 21 February 2011
Two wet chemical cleaning processes (a conventional chromic acid clean and an electrochemical etch) and a H-plasma exposure have been employed to clean natural type lib semiconducting diamond C(001) wafers. The effects of these processes on the diamond surface have been assessed and compared. As evidenced by Auger electron spectroscopy (AES), an oxygen free surface could be obtained following annealing to 900°C for the electrochemical process compared to 1050°C for the chromic acid etch. In addition, the technique of Atomic Force Microscopy (AFM) demonstrated the presence of oriented pits on the surface of samples electrochemically etched for long times at high currents. Furthermore, heteroepitaxial Cu films have been grown on the diamond substrates cleaned by a process as described above. By means of Ultraviolet Photoemission Spectroscopy (UPS) a Schottky barrier height of ΦB≊ 1.0 eV was measured. Furthermore, the presence a negative electron affinity (NEA) has been determined.