Influence of annealing on the electronic properties of chemical vapor deposited diamond films studied by high vacuum scanning tunneling microscopy and spectroscopy

Scanning tunneling spectroscopy (STS) under high vacuum conditions (2x10(-8) mbar), combined with high-resolution topographical imaging with the scanning tunneling microscope (STM), enabled us to investigate local variations in the electronic structure of the surface of chemical vapor deposited diamond films. We studied the variations in the current-voltage I(V) characteristics of hydrogen terminated films when varying the distance between bp and surface. Our STS measurements confirm the surface p-type conductance. We also studied the influence of changes in the hydrogen termination by annealing under high vacuum conditions. Annealing at relatively low temperatures is shown to dramatically influence the local I(V) characteristics measured with STM. confirming that hydrogen termination alone is not sufficient for explaining the enhanced surface conductance. (C) 2002 Elsevier Science B.V. All rights reserved.