Investigations on the origin of the ohmic behavior for Ti/Al based contacts on n-type GaN
Résumé
This work reports of investigation on the origin of the ohmic behavior for Ti/Al based contacts on n-GaN. Indeed, last publications tend to prove that the "nitrogen vacancy" theory is not confirmed by the experimental ground available. To find new answers, we first made electrical characterizations on some Al/Ti/n+-GaN contacts with different annealing conditions. Then, we performed SIMS depth profiles of annealed TiN/Ti/n+-GaN samples. Results developed in this paper tend to demonstrate that the ohmic behavior of Ti/Al based contact is mainly due to an increase of the doping concentration. Moreover, the high doping level can be explained by an in-diffusion of Ti and an exo-diffusion of Si elements close to the metal / semiconductor interface.