Deuterium depth profiles at CVD diamond surfaces

Abstract

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)×10 15 at/ cm 2 of deuterium on the (1 0 0) diamond surface, which is in agreement with a deuterium terminated (2×1) reconstructed (1 0 0) diamond surface. The hydrogen and deuterium bulk concentration is only about 1.0×10 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.