Enhanced dynamic annealing and optical activation of Eu implanted a-plane GaN
Instituto Tecnológico e Nuclear/IST - Estrada Nacional 10, 2686-953 Sacavém, Portugal, EU
2 Departamento de Física de Materiales, Universidad Complutense - 28040 Madrid, Spain, EU
3 Centro de Física Nuclear da Universidade de Lisboa - Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal, EU
Accepted: 15 February 2012
The implantation damage build-up and optical activation of a-plane and c-plane GaN epitaxial films were compared upon 300 keV Eu implantation at room temperature. The implantation defects cause an expansion of the lattice normal to the surface, i.e. along the a-direction in a-plane and along the c-direction in c-plane GaN. The defect profile is bimodal with a pronounced surface damage peak and a second damage peak deeper in the bulk of the samples in both cases. For both surface orientations, the bulk damage saturates for high fluences. Interestingly, the saturation level for a-plane GaN is nearly three times lower than that for c-plane material suggesting very efficient dynamic annealing and strong resistance to radiation. a-plane GaN also shows superior damage recovery during post-implant annealing compared to c-plane GaN. For the lowest fluence, damage in a-plane GaN was fully removed and strong Eu-related red luminescence is observed. Although some residual damage remained after annealing for higher fluences as well as in all c-plane samples, optical activation was achieved in all samples revealing the red emission lines due to the 5D0→ 7F2 transition in the Eu3+ ion. The presented results demonstrate a great promise for the use of ion beam processing for a-plane GaN based electronic devices as well as for the development of radiation tolerant electronics.
PACS: 81.05.Ea – III-V semiconductors / 61.72.U- – Doping and impurity implantation / 78.60.Hk – Cathodoluminescence, ionoluminescence
© EPLA, 2012