Hydrogen analysis of CVD homoepitaxial diamond films by high-resolution elastic recoil detection

Abstract

We have measured hydrogen depth profiles in chemical vapor deposition (CVD) diamond films by high-resolution elastic recoil detection. The depth resolution of nearly 0.2 nm is achieved by means of a high-resolution magnetic spectrometer. The hydrogen profile in the as-grown sample shows a sharp peak at the surface. The peak has a small tail toward larger depth, showing that some hydrogen atoms are incorporated in the subsurface region. There is no difference in the hydrogen depth profiles between the undoped and B-doped diamond films. After surface hydrogen is removed by an acid solution, the CVD diamond is rehydrogenated using a hydrogen plasma at 800 °C. The rehydrogenated sample shows almost the same hydrogen profile as the as-grown sample. The hydrogen profile hardly changes by annealing at ∼400 °C, though a small change in the subsurface region cannot be excluded.