Electrical conduction of high-conductivity layers near the surfaces in hydrogenated homoepitaxial diamond films

In order to clarify the origin of high-conductivity layers HCL.near the surfaces of hydrogenated diamond films, we have studied the relationship between HCL and surface structure in B-doped homoepitaxial 001. diamond films. Samples annealed in nitrogen environment at various temperatures have been characterized by Hall-effect measurements and reflection high-energy electron diffraction. It was found that HCL disappeared in the films annealed at a temperature higher than 3508C, but the 001.-2=1 surface-structures observed in hydrogenated films remained at 3508C. This indicates that HCL is not related directly with the 001.-2=1 surface-structure. The origin of HCL will be discussed on the basis of the present results. q2000 Elsevier Science B.V. All rights reserved.