Identification of etch‐pit crystallographic faces induced on diamond surface by H₂/O₂ etching plasma treatment

Abstract

Abstract Even for samples exhibiting excellent electronic properties in terms of carrier mobility, sample‐to‐sample variability remains considerable and dislocation density is still very high, the latter characteristic being often related to damages induced either by the substrate polishing step or by substrate bulk dislocations. In order to limit the polishing effect, a pre‐treatment based on H 2 /O 2 plasma etching under relatively high pressure (a few 100 mbar) has been routinely used for several years. Nevertheless, those bulk dislocations present in the substrate that reach its surface lead to square etch‐pit formation which depth can grow to several 100 nm, preventing the growth of smooth and flat thin films (<few µm). In order to overcome this limitation, we have focused our work on the identification of the crystallographic faces constitutive of the etch‐pits. Starting from a geometrical model describing the diamond crystal morphology evolution, and by carefully choosing the initial growth conditions, we show that it is possible to fill the etch‐pits rapidly and thus to recover the H 2 /O 2 plasma pre‐treatment advantages, even for thin film deposition with smooth surface.