Deuterium depth profiles at CVD diamond surfaces

Homoepitaxial diamond films grown by chemical vapour deposition (CVD) in a methane deuterium plasma were investigated for their deuterium and hydrogen content using high resolution elastic recoil detection (ERD) with a depth resolution of about 0.5 nm. The as-grown diamond films showed large surface conductivity as it is used for diamond surface channel field effect transistors. The ERD measurements revealed an amount of (1.7 +/-0.2) x 10(15) at/cm(2) of deuterium on the (100) diamond surface, which is in agreement with a deuterium terminated (2 x 1) reconstructed (1 0 0) diamond surface. The hydrogen and deuterium bulk concentration is only about 1.0 x 10(19) at/cm(3), even at a depth of 1.5 nm below the surface. Therefore, it can be concluded, that the highly conductive p-type layer in as-deposited CVD diamond films is not due to additionally incorporated hydrogen in the subsurface region in contrary to many conduction models. (C) 2001 Elsevier Science B.V. All rights reserved.