AFM and XPS studies of a homoepitaxial diamond (001) surface nitrided using 500-eV N-2(+) ion beam

A homoepitaxially grown p-type diamond (001) surface was nitrided by irradi ation with a 500-eV N-2(+) ion beam X-Ray photoelectron spectra (XPS) were taken in situ during the nitridation. The C1s and N1s XPS spectra were divi ded into three (A, similar to 284.7; B, similar to 285.6; and C, similar to 287.3 eV) and four (D, similar to 398.4; E, similar to 399.5; F, similar t o 401.0; and G, similar to 403.3 eV) components, respectively. The A compon ent of the C1s core level originated from the diamond substrate lying under the nitrogen penetration zone. The B and C components came from the nitrog en-diluted layer and from the carbon nitrides, respectively. The compositio n ratio of nitrogen/carbon in the C phase, ND+F/C-C, was 0.71. The N-all/CB +C ratio was 0.25. The morphology of the surface was also measured in air b y atomic force microscope (AFM). It was found that grain-like material cove red the surface after nitridation. A typical grain size was approximately 5 0 nm in diameter with a height of 5 nm. However, the grains themselves were not carbon nitrides. The crystallinity of the nitride was investigated usi ng reflection high-energy electron diffraction (RHEED), but the formation o f beta -C3N4 could not be confirmed from the RHEED patterns, due to overlap ping with the twin structures of diamond. (C) 2001 Elsevier Science B.V. Al l rights reserved.