Hydrogen mobility in diamond studies using HI-ERDA microscopy

Hydrogen plays a significant role in the growth of diamond and in the determination of its physical, electrical and optical properties. However, despite this significance, the configuration, chemistry and behaviour of hydrogen in the diamond lattice is still not very well understood. In this work, the stability of a collimated hydrogen implant distribution, as well as the intrinsic hydrogen distribution in a single crystal natural type IIa diamond are studied by imaging with the micro-scanned Heavy-Ion Elastic Recoil Detection Analysis (μHI-ERDA) technique in three dimensions. To investigate possible trapping of hydrogen at vacancies a shallow pre-damaged layer was created between the implanted hydrogen distribution and the surface by collimated bombardment of the sample with 50 keV ¹²C ions. No evidence of migration of the implanted or the intrinsic hydrogen to the pre-damaged region was observed even after annealing at 1473 K. The stability of the implanted hydrogen indicates the deep trapping of this species within its own implanted range distribution. The results confirm similar measurements previously performed on a natural type Ia diamond as well as on a synthetic type Ib diamond. The current sample was exceptionally pure, enabling an extension of these measurements to a situation where the intrinsic hydrogen concentration, as well as the hydrogen trapping behaviour might be expected to be different. Our results suggest complex trap configurations for hydrogen in diamond, not necessarily associated with nitrogen related defects.