Nitrogen and hydrogen distribution and retention in dense N delta doping by layer overgrowth onto a diamond (100) surface

Abstract

We investigate the influence of surface chemical and structural properties of initial nitrogen terminated diamond surfaces on the nitrogen and hydrogen distribution in the N delta layers fabricated onto diamond (100) surfaces by different surface nitridation methods followed by a diamond layer overgrowth. Surface analysis shows that annealing of highly-damaged surfaces results in graphitization and promotes nitrogen incorporation into graphitic sites whereas lower damaged surfaces result in recovery of the near surface diamond structure alongside with nitrogen bonded mostly in a single configuration. Surface damage enhances hydrogen incorporation into the N delta layer. The etching of the disordered layer (formed during the nitrogen termination) occurs during the initial stages of diamond over growth. The nitrogen retention ratio efficiency in the delta layer depends on the crystallinity of the nitrogen terminated surface and bonding: is higher when nitrogen is bonded in the sub-surface region. Hydrogen diffusion into the N delta layer occurs following the nitrogen distribution most likely bonding to nitrogen and defects. At optimal conditions, the FWHM of N delta layer in diamond (100) is ~3 nm with a maximum nitrogen and hydrogen concentration of ~1.2×1020 atoms.cm−3 and ~2.0×1021 atoms.cm−3, respectively. The overgrown layers possess high crystallinity.