Hydrogen implantation into ZnO for n+-layer formation

Bulk ZnO crystals were implanted using 100keV H+ ions with doses 5×1016 and 2×1017cm−2 and subsequently annealed at 200–600°C to study the evolution of the implanted H by employing secondary ion mass spectrometry and scanning spreading resistance microscopy. It is shown that the heat treatment results in a decrease of H concentration in the implanted region, while no significant broadening of the H profiles is observed. This suggests that the implanted H is trapped in immobile complexes which dissociate during annealing with subsequent outdiffusion of H from the implanted region. The formation of a highly conductive n+-layer is observed in the implanted region, and the n+-layer is found to be stable up to 600°C. A correlation between electrical activity of H and presence of radiation damage is discussed.